They have not been deleted, as they are not present in your computer it indicates there is a problem with your system. Try removing the search.sqlite file as shown in the "Unable to search" section of this link - http://kb.mozillazine.org/Unable_to_search_or_add_new_engines

That file contains details about the installed search engines, deleting the file will force Firefox to rebuild the list.

None of the suggestions has changed this error.

In addition when I try to use Contact Us, the Browser forwards me to the upgrade page, when the About Firefox says I have the current version. Help!

Do you still see the xml files of the default search engines in the searchplugins folder in the Firefox program folder?

Your user agent identifies you as Firefox 4.0 and not 4.0.1:

• Mozilla/5.0 (Windows NT 5.1; rv:2.0) Gecko/20100101 Firefox/4.0

See:

• Web sites or add-ons incorrectly report incompatible browser

I do not see any xml files of the default search engines in the searchplugins folder in the Firefox program folder.

I do not understand your second comment. The image show the return for the About Page for Firefox

You don't have the "official" version of Firefox, you have the Yahoo!Edition of Firefox 4.0.1. That might be why your UserAgent (which this forum software displays in the More system details box in the first posting in each thread) shows 4.0 & not 4.0.1 as the About Firefox does, and why the \searchplugins\ folder is empty.

Try installing the official version and download it directly from Mozilla.
http://www.mozilla.com/en-US/firefox/

I found my way to

"Web sites or add-ons incorrectly report incompatible" browser page and the items that were to be reset were "greyed out".

If I install the official version will I loose my "Bookmarks"? Can I save and reinstall them ?

And thanks for the help so far.

If those prefs aren't bold, they are default pref values. Most of the information in that support article isn't applicable in Firefox any longer, as it is almost impossible for anything "added" to Firefox 4 to mess with the default settings like with previous versions. I figure that Yahoo messed up something in the omni.jar file or didn't update the UA string for 4.0.1. Mozilla has locked the UA string down by putting it in the "hard to access programically" omni.jar file to keep "everybody" from changing it and causing a variety of different problems for Firefox users.

No, you won't lose any personal data such as bookmarks, as long as you don't select the option to "remove Firefox personal data and customizations" when uninstalling your current version of Firefox.

Heaven regained!

Thanks very much.

You're welcome.

Please click the Helpful button next to the answer that solved your Firefox support issue, when you are logged in, so this thread gets marked as Solved to help other users who may have this same problem.