>Our application is running on VFP ver 6.0 SP5. About 200 PCs is running without errors, but on some PCs (10 or 15) APP crashes due "Fatal error: Exception code=C0000005". When user restarts program, the part, which reported error, is running correctly.
>Can you help me to avoid this error?

This error is windows saying "Help something is very wrong" The most common causes for the C5 erros are drivers (printer, video) that conflict with software that is running (in your case VFP). One very common problem set of drivers are HP printer drivers. The solution is to change the printer dirver to one that ships with windows and see if the errors stop. If not try changing the video driver.