I know some people were having issues with certain add-ons like torbutton. I actually don't have any add-ons installed for Firefox. I have tried resetting Firefox, restarting it in safe mode, disabling all of my plugins, and reinstalling it all together. Nothing has worked. I am using Windows 8 consumer preview, not sure if that has anything to do with it. I only recently started having this problem, and I haven't done anything to modify or change Firefox recently.