Faulting application excel.exe
 

I currently have a problem with excel GPF'ing frequently.

Faulting application excel.exe, version 11.0.8307.0, stamp 49ee85df,
faulting module user32.dll, version 5.2.3790.4033, stamp 45e7c676, debug? 0,
fault address 0x0001c29d.

Excel is hosted on a Windows 2003 Service Pack 2 server with Terminal
Services and Citrix installed and is available to a number of users. Any
ideas? I have tried googling for an answer without success