I have had strange errors too. Usually could be tracked down to two things:
- not enough memory available
- something funky happening in the code (in my case the getenv command was acting up)

>We occasionally get the following message from our Foxpro application: This program has performed an illegal operation and will be shut down. The details start of by saying SPARASYS caused an invalid page fault in module VFP500.dll at 0137:1009a220. Do we need an updated version of that dll? What can we do?
>
>We our running,
> Visual FoxPro 5.0 executable
> Windows 95
> Novell netware