If using Zone Alarm's browser virtualization or any other similar product or a sand-boxing program (i.e., Sandboxie), turn it off when updating Firefox or Firefox Add-ons. You can post on the forum for any such product that you might be using to get other instructions on the proper use of the product. The updater wasn't able to update all the files and some were left as older versions. Do a clean reinstall. See: [http://kb.mozillazine.org/Browser_will_not_start_up#XULRunner_error_after_an_update Browser will not start up - XUL Runner error after an update] #Download a fresh Firefox copy and save the file to the desktop. #*Firefox 6.0.x: http://www.mozilla.com/en-US/firefox/all.html #Uninstall your current Firefox version. #*'''''Do not remove personal data when you uninstall the current version''''' #*Your bookmarks and other profile data are stored elsewhere in the Firefox Profile Folder and won't be affected by a reinstall, but make sure that you do not select to remove personal data if you uninstall Firefox. #*See [http://support.mozilla.com/en-US/kb/uninstalling+Firefox Uninstalling Firefox] '''''and''''' [http://kb.mozillazine.org/Uninstalling_firefox Uninstalling Firefox (Mozillazine)] #*Also see: [http://support.mozilla.com/en-US/kb/Backing+up+your+information Backing up your information] '''''and''''' [http://kb.mozillazine.org/Profile_backup Profile backup (Mozillazine)] #Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer. #*It is important to delete the Firefox program folder/directory to remove all the files and make sure that there are no problems with files that were leftover after uninstalling. #*See: http://kb.mozillazine.org/Installation_directory #Install the fresh copy of Firefox that you downloaded in step 1

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