Download latest Firefox version using one of these links:

• http://www.mozilla.com/en-US/firefox/new/
• http://www.mozilla.com/en-US/firefox/central/
• http://www.mozilla.com/en-US/firefox/fx/
• http://www.mozilla.com/en-US/firefox/all.html

Uninstall your current Firefox

• https://support.mozilla.com/en-US/kb/Uninstalling%20Firefox
• DO NOT SELECT TO REMOVE USER DATA AND SETTINGS
• Restart your system

Install Firefox using the downloaded & saved Firefox installer file

• https://support.mozilla.com/en-US/kb/Installing%20Firefox%20on%20Windows

Check and tell if its working.

Thanks. I'll try it later in the morning.

Finally remembered that Internet Explorer exists, otherwise, couldn't get into the internet. Bottom line: both Mozilla Firefox version 3.6.13 and 6.0.2 are installed. When I went to remove each of them (Control panel, add or delete programs), I got the following message both times: "Your computer must be restarted to complete previous upgrade. Do you want to reboot now?" If I say yes, the computer reboots. Then when I go to remove one of the programs (again) I get the same message. If I say no and go to remove one of the programs, (again) I get the same message. Any ideas?

The program must close to allow a previous installation attempt to complete

• https://support.mozilla.com/en-US/kb/The%20program%20must%20close%20to%20allow%20a%20previous%20installation%20attempt%20to%20complete

Installing Firefox on Windows

• http://kb.mozillazine.org/Installing_Firefox#Windows

Uninstalling Firefox on Windows

• http://kb.mozillazine.org/Uninstalling_firefox#On_Windows

Check and tell if its working.

Run the Firefox program once as Administrator (right-click: Run as Administrator).
If that doesn't solve the problem then remove the Firefox program folder to do a clean reinstall.

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.

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.

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