>
> The case I've seem was:
> * Windows Server 2008 R2 (64bit, as far as I remember)* Firebird 1.5.6 Classic (32bit, of course)
>

Hello Will

The following article explains the living of Windows 32bit apps on Windows 64bit systems: http://msdn.microsoft.com/de-de/site/cc300794
I didn't take the 2 Minutes ;-) yet to read it completely, but I think that a 32bit Firebird server will only change settings of the 32bit subsystem (Windows[32] on Windows64) = WoW64.

Try a 64bit Firebird server, I hope it helps. I have to migrate in some weekt to Server 2008 R2 64bit in some weeks, so please post your solution

Good luck
Christian