According to the experts this is what you need to do, in summary.

1. Close Firefox; completely. Open the Task Manager and kill any firefox.exe processes, if still running.

2. Browse to your Profile Folder [in windowsXP under C:\Documents and Settings\%username%\Application data\Mozilla\Firefox\Profiles\
randomname.default\ ] and delete the file parent.lock, if it exists.

3. Run the Profile Manager [in windows: Start | Run | type firefox.exe -p | ok] and choose the default profile.

If the Profile Manager does not appear, repeat without skipping step 2

Taken from here

http://forums.mozillazine.org/viewtopic.php?t=261801

But it did not work for me. I have reimported my bookmarks from IE and I am in the process of starting again. I suppose though like most people I did not backup my bookmarks.

On the plus side spellbound now works, which after about 10 attempts before I could never get to work.