Seems that within the last 3 weeks, can't be certain exactly, Firefox has been crashing rather randomly. Just web browsing, the Firefox window will suddenly go crooked or get static lines and flicker on and off. Stopping and restarting Firefox and it's fine again. Haven't experienced this in any other program. Thoughts on where to look for clues?

Did you start it via terminal so that you can see the error messages there? Might be helpful.