I have a 2011 MBP (see sig), I've noticed twice in the last couple of days that in the middle of a session, the last time just browsing with Firefox, that I got a blue screen that did not go away. I admit I did not wait a long period of time before force restarting. On restart the problem goes away. Any ideas on a likely culprit? I have looked around for "blue screen" links, but the ones I found had to do with a blue screen on start. This is not my case. Thanks!