We (my wife and I) have been dealing with this issue for the last year. It's gotten to the point we are ready to migrate back to IE! Situation: Boot system open FF browser enjoy FF with its addon and browsing ease. leave FF on and leave for a couple hours upon returning, click on a new site or try to change pages on same site and it shows it is trying to load the page but NEVER does... So you close FF, upon trying to open again it says another copy is running, so we bring up taskmgr, find the FF highlight it, click end process and finally we can open FF again. I have tried it with our plugin's and w/o our plugins and it doesn't seem to make any difference.