Never heard of that happening. But problems with bookmarks have been provided for to a limited extent, by having some bookmark backups available even for people that don't backup.

In your profile are 5-10 bookmark backups try restoring to an earlier date. "Ctrl+Shift+B" (show all bookmarks) > Import and Backup > Restore > choose date the problem occurred or the day before, if that doesn't work try the next day back.

The Restore is done by Firefox with Firefox up and running , a restore goes very fast.

Backups are taken once a day early in the day.

FWIW, you should also have your own backups of your user data from all applications external disk drives are cheap. Backing up your Firefox profile would easily fit on a thumb drive. But you really should be backing up all user data youself.

Thanks - that seems to have worked. I'm on a small network here at work, and they do daily backups of our network server - which would include our profiles, so our user data would be backed up as well. Just saw the problem today and my IT doesn't technically support Firefox (I'm lucky they let me keep it on my computers), so I can't bug them with any issues about it.

A possible cause is a problem with the file places.sqlite that stores the bookmarks and the history.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox