application fault in firebird

this varies from time to time that IE is used, sometimes will pop up 
when you start, sometimes later.  No set amount of time, and i can't 
find any connection with any certain action that may be causing it.
The actual error reads:

Application Failure  firebird.exe 0.8000 in msvcrt.dll 7.0.2600.1 
Offset: 00033ec0

I have this happening on 3 machines.  I have tried a repair install of 
XP, a reinstall of IE (using the instructions from the knowledge base), 
running SFC, getting a copy of msvcrt.dll from a machine that is not 
having the problem.  I have installed all the security and service packs 
for xp and IE, I've run Ad-aware and Spybot, I've run HijackThis, 
nothing is installed/running to interfere with IE.

I just got done running a memory and system diagnostic and it came up 
clean.  I have no idea where to look now.