VMs either have no GPU support at all, or AFAIK their GPU support is pretty buggy, like having really bad drivers. So I would assume it's that, unless you can get any crashes on a non-virtual OS... and even then, I would still say it's a driver bug :P
It's a real shame how cool GPU technology is, but how crappy drivers and support make it hard for everyone to use it. Anyway, I'm going to close this report for now.