Comment 4 for bug 73322

I have had the same problem as you two. Unfortunately, i can't find any solution but uninstalling the existing Firefox on your system (performing a clean installation, i mean -- you have to completely remove the Firefox user profile or else the error won't go away -- The profile will be located within your documents and settings/<your user name>/Application Data/mozilla) then re-install firefox again. If it ask you to import IE profiles on the startup means it's work.