Quite frequently Firefox does not shut down when the active window is closed. Attempts to open another program that uses Firefox is then blocked from opening until I shut down and reboot my computer as the drop down box instructs. I have tried everything I can, but none of the suggestions currently offered seem to apply to my problem. This has only been since the lat update to Firefox a little over a week ago. I am running Widows 7 with all current important or urgent updates (not including Internet Explore updates/upgrades).