hello, this sounds like the files in your profile folder that store the information about your extensions might have become corrupted. please go to firefox > help > troubleshooting information > profile - show folder... then windows explorer should open up your profile folder. in there look for the files named extensions.ini, extensions.sqlite, extensions.sqlite-journal (and in some cases also extensions.txt, extensions.rdf). delete or rename those files and quit firefox, they will be regenerated the next time you launch firefox.

also see Corrupt extension files

Ok Thanks...I'll give that a try. Ya know it's real dumb for yahoo messenger to even do such a thing. Well for the toolbar that it installs without you not being able to choose not to have it. Not everybody uses the toolbars if they are on the websites. And this happens. I see it happens to everybody.