• 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.
XP:

C:\Documents and Settings\<user>\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates
(%USERPROFILE%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox)

If you have problems with updating then best 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.

Do a clean (re-)install: 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.

Sorry for the delay (hubby in emergency open heart surgery) I followed your easy-to -understand directions ( being a nimrod of sorts) and the problem seems to have gone away. Thank you so much!

You're welcome