Comment 14 for bug 296578

"Another thing I noticed recently is every time I restart after a crash, right before the login window loads, the screen flashes for a fraction of a second with a somewhat distorted image of my screen when it was frozen."

That is interesting, because the only thing that could cause that behavior is the x-server(or gdm perhaps), i guess.

"I've also noticed that I only seem to be crashing when connected to my school's vpn connection."

Also interesting. I bet you're browsing some specific websites at school, right? Perhaps some heavy flash in firefox can cause this?
But, this should probably have something to do with NM/driver and VPN afterall, i just don't know how to troubleshoot that...