>i m not an expert in call stack, but what i see (in the CPU windows) it that after the end of the function
>EventCallBack we go imediatly in the call to fbclient.gds__thread_exit and after we go in the Access Violation in ntdll.dll !

Download debug kit for the same Firebird version as you used on client side.
Put fbclient.pdb at the same folder as fbclient.dll. Follow instructions below to
setup drWatson and produce crash dump and crash log. Attach crash dump and
log files to the bug ticket at tracker.

Instructions

http://www.ibphoenix.com/main.nfs?a=ibphoenix&s=1254244067:355713&l=;PAGES;NAME=%27ibp_pdb_win32%27

Regards,
Vlad