Why is my history blank?
My history has stopped working, and no longer shows or keeps the sites I have seen in either the recent history or show all history and stays blank. The address bar is unaffected though. What is wrong and how do I fix it?
You might have a damaged Places.sqlite file which stores the bookmarks and history. Try Export Firefox bookmarks to an HTML file to back up or transfer bookmarks and then removing Places.sqlite from your profile folder.
More detailed instructions here: http://kb.mozillazine.org/Locked_or_damaged_places.sqlite
SOLVED. I tried the above solution (or one similar to it) and it didn't help. But I think there's a fix. It appears that this is a problem with the Google toolbar AutoFill.