It is normally not necessary to uninstall Firefox before installing an updated version, unless you have problems and a very strong reason to think this will resolve the issue. (e.g. advice from the Firefox or Mozillazine KnowlegeBoard articles) You should if necessary be able to kill firefox.exe process (and any plugincontainer.exe) with for instance task Manager. * see [[firefox is already running but is not responding]] You should also consider backing up your profile, and your bookmarks prior to any clean re-install. In addition you may consider the use of Firefox Sync to ensure any other machines are synced. * see [[what is firefox sync?]] * [[backing up and restoring bookmarks]] There are two types of clean install # deleting your programs folders, <br/> that may help if some left over files in that folder are causing problems. # deleting profile data /!\ CARE this will destroy records of passwords, bookmarks and many other records potentially stored by firefox. <br/>A safer test and temporary solution is to create a new profile without changing the existing one. If that helps consider proceeding carefully, and using backups to recreate as much as possible. *see http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall * [[backing up your information]]