Well, I've been having a similar problem, but I'm still using XP. Firefox doesn't tell me it's stopped - it just freezes. I can't do anything else that involves the internet until the computer is restarted. And I usually can't accomplish this in the proper way. I have to unplug the computer. I also use AVG. I wouldn't say AVG freezes, but it seems to get "stuck" and doesn't turn off after a routine scan. I've been more thinking this is an AVG problem and as soon as I can get to Office Max or Walmart, I'm going to get another anti-virus and try that.
