I up graded from firefox 3.6 to firefox 5 and now it will not work on my computer. I have tried to start it and nothing happens. I have tried everything on the troubleshooting web site to no avail. I have tried now loading 4 and it won't work either. I have had to switch to Google Chrome. I lost all my bookmarks. I am really disappointed, I have used Firefox for years... I am running an HP with Windows vista 64 bit.'''bold text'''