hello, could cou please post the exact wording of the error message? - this will probably make it easier to troubleshoot the issue...

This is the error message I get: Software Update Failed

The update could not be installed. Please make sure there are no other copies of Firefox running on your computer, and then restart Firefox and try again.

Now, when I ckick OK, Firefox opens to version 12.0. So, I uninstalled 12 and installed 13.0 and got an even stranger message (I don't remember--but it was a system error msg) and Firefox would not open at all on my system, it was as though it no longer existed. So I don't know what to do. I'm no whiz when it comes to technology, so any help you could give me would be truly appreciated.

Thank you Streim

Do a clean (re)install and delete the Firefox program folder (C:\Program Files\Mozilla Firefox\).

Download a fresh Firefox copy and save the file to the desktop.

• Firefox 13.0.x: http://www.mozilla.org/en-US/firefox/all.html

Uninstall your current Firefox version, if possible.

• Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you will also lose your personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

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.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

I did exactly as you said cor-el. However, now I get a message that says XUL Runner Error: Platform version '12.0' is not compatible with minVersion>=13.0 maxVersion>=13.0

I can't even open Firefox at all. Any suggestions. I also went to all the links in the e-mail that you suggested.

If you use ZoneAlarm Extreme Security then disable Virtualization and reinstall Firefox.
Other security software may have similar features to prevent Firefox from updating files properly.

See:

• http://kb.mozillazine.org/Browser_will_not_start_up#XULRunner_error_after_an_update

Thank you so much for your help!! It worked!! :)