You are right to be confused (my fault) I had FF 3.6 upgraded to FF4 thats the time i got problems - I then WENT back to FF3.6 now my only problems are (1) I keep getting the log-in box each time i CHANGE pages in Yahoo. (2) when I start up I get a full page of add-ons on the screen.
I did upgrade to FF5 in the meantime in trying to solve it myself - but COMPATIBILITY became an issue so went back to FF3.6. Now USING FF3.6 as STATED above.