I use Auctioneer Classic Suite on 2 servers (1 alliance / 1 horde), on the alliance server Auctioneer works fine while on the horde server i get lots of error messages when I open the Auction House window.
I use the same addons on both servers, so I've no idea why this happens. I've deleted all Auctioneer / Enchantrix releated files some times, to start with a fresh Auctioneer but the problem stays the same. (b.t.w. the same happened with the previous Auctioneer ClassicSuite 5.0.PRE versions I tried).

Error messages on horde server when I open the Auction House window (BugSack):

-01/19-
[2007/10/13 00:38:03-2009-x1]: Auctioneer\AucLocale.lua:34: Cannot find a library instance of "Babylonian".
LibRock-1.0--48665 (FuBar):329: in function `LibStub'
Auctioneer\AucLocale.lua:34: in main chunk
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-02/19-
[2007/10/13 00:38:03-2009-x1]: Auctioneer\AucCore.lua:169: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-03/19-
[2007/10/13 00:38:03-2009-x1]: Auctioneer\Database\AucSnapshotDB.lua:120: attempt to index field 'Core' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-04/19-
[2007/10/13 00:38:03-2009-x1]: Auctioneer-5.0.PRE.2319\AucMain.lua:111: attempt to call global '_AUCT' (a nil value)
<string>:"*:OnLoad":2: in function <[string "*:OnLoad"]:1>
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-05/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameSearchBid:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-06/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameSearchBuyout:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-07/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameSearchCompete:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-08/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameSearchPlain:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-09/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameSearchOwner:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-10/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameSearch:OnLoad":3: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-11/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameTabSearch:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-12/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFramePostCreateAuctionButton:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-13/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFramePost:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-14/19-
[2007/10/13 00:38:03-2009-x1]: <string>:"AuctionFrameTabPost:OnLoad":1: attempt to call global '_AUCT' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-15/19-
[2007/10/13 00:38:04-2009-x1]: BeanCounter\BeanCounterLocale.lua:33: Cannot find a library instance of "Babylonian".
LibRock-1.0--48665 (FuBar):329: in function `LibStub'
BeanCounter\BeanCounterLocale.lua:33: in main chunk
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-16/19-
[2007/10/13 00:38:04-2009-x1]: <string>:"AuctionFrameTransactionsSearch:OnLoad":1: attempt to call global '_BC' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-17/19-
[2007/10/13 00:38:04-2009-x1]: BeanCounter-5.0.PRE.2319\AuctionFrameTransactions.lua:143: attempt to call global '_BC' (a nil value)
<string>:"*:OnLoad":1: in function <[string "*:OnLoad"]:1>
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-18/19-
2007/10/13 00:38:04-2009-x1]: <string>:"AuctionFrameTransactions:OnLoad":1: attempt to call global '_BC' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

-19/19-
[2007/10/13 00:38:04-2009-x1]: <string>:"AuctionFrameTabTransactions:OnLoad":1: attempt to call global '_BC' (a nil value)
<in C code>: in function `LoadAddOn'
Stubby-2225\Stubby.lua:876: in function <Interface\AddOns\Stubby\Stubby.lua:875>
Stubby-2225\Stubby.lua:896: in function <Interface\AddOns\Stubby\Stubby.lua:881>
Stubby-2225\Stubby.lua:925: in function `f'
Stubby-2225\Stubby.lua:730: in function `EventWatcher'
Stubby-2225\Stubby.lua:953: in function `Events'
<string>:"*:OnEvent":1: in function <[string "*:OnEvent"]:1>

---

This happens with FuBar enabled, but when I disable Fubar I still get those errors.

After I try to open the Auction House window when Auctioneer doesn't work I get error messages in my chat frame when I mouseover an item in my inventory or character frame like this one:

Error while calling hook for: EnhTooltip.AddTooltip. Interface\AddOns\Auctioneer\AucUtil.lua:302: attempt to index field an item in my i'Core' (a nil value)
Call Chain:
Interface\AddOns\Auctioneer\AucUtil.lua:302: in function `GetAuctionKey'
Interface\AddOns\Auctioneer\AucStatistic.lua:409: in function `GetUsableMedian'
Interface\AddOns\BtmScan\EvalResale.lua:79: in function `valuate'
...
[C]: in function `xpcall'
Interface\AddOns\Stubby\Stubby.lua:359: in function <Interface\AddOns\Stubby\Stubby.lua:324>
(tail call): ?
Interface\FrameXML\PaperDollFrame.lua:1161: in function `UpdateTooltip'
Interface\FrameXML\GameTooltip.lua:118: in function `GameTooltip_OnUpdate'
[string "*:OnUpdate"]:1: in function <[string "*:OnUpdate"]:1>


I found the problem has nothing to do with the server (horde/alliance) now.
The errors appear when I have Gatherer turned off in the addon screen, I've tried it on both servers now and when I have Gatherer (3.0.1) and Auctioneer Classic Suite (5.0.PRE.2319) installed but don't turn Gatherer on I get those errors.
But when I only install those 2 addons (clean "\World of Warcraft\Interface\AddOns\" and "\World of Warcraft\WTF\" folder with only Auctioneer and Gatherer in there) and turn Gatherer off everything works fine, so it looks like a conflict with another addon I use.
So I just turn Gatherer on now on all my characters and Auctioneer works fine. Not the best solution to the problem, but for now it looks like the best thing I can do.
And while I'm typing this I found another way to solve the problem.... when I load Enchantrix before I open the Auction House window Auctioneer works fine also... so that even looks like a better solution, I will give any character that doesn't use Gatherer the "/Enchantrix load always" command.

I'm not a computer wizard, but as far as I know Stubby is the part that loads the other parts of Auctioneer when they're needed..... is it possible Stubby loads them in a wrong order ?

I was having similar issues. This turned out to be old versions of the Auctioneer files (i.e., there was a babylonian directory at the Beancouter level as well as in the Beancounter/libs directory). I think a full removal of your Aunctioneer and a reinstall might help.