See:

• http://kb.mozillazine.org/Software_Update (Software Update not working properly)

Remove the files in the updates and updates\0 folder.
You may need to delete active-update.xml and updates.xml as well if present.

Vista:

C:\Users\<user>\AppData\Local\Mozilla\Firefox\Mozilla Firefox\updates
(%LOCALAPPDATA%\Mozilla\Firefox\Mozilla Firefox)

If you have problems with updating then easiest is to download the full version and uninstall the currently installed version. You may need to remove the Firefox program folder to do a clean install of the new version.

• Download a fresh Firefox copy and save the file to the desktop.
• Firefox 4.0.x: http://www.mozilla.com/en-US/firefox/all.html

• Uninstall your current Firefox version and remove the Firefox program folder before installing that copy of the Firefox installer.
• Do not remove personal data if you uninstall the current version.
• 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.

I downloaded a new version of Firefox. When I attempted to remove the old program it doesn't appear in the list of programs under "add/remove programs". How do I remove the old program that doesn't seem to be able to get updates? And, where is the Firefox program folder? When I downloaded the new program it did not give me the option of saving to the desktop. It put it in a folder labeled"downloads".

I am now using Google's Bing I am problem free.

Sorry...I meant Microsoft's BING!