I have set a master password for Firefox on my mac (FF4, OS X 10.6). This has worked for years, but suddenly today I cannot unlock it anymore. I've had this a while back on a Ubuntu Desktop, and solved it back then by replacing the profile with a backup. I've tried to do this today, multiple times, with backups from timemachine. I restored the files in my user library, Application Support, the folders Mozilla and Firefox. I used a backup from several days ago, when the master password could be unlocked. I am absolutely sure that I use the correct password. But it doesn't work for some reason. I have disabled all add-ons, but no luck.
Do you have any ideas how to get this solved? Is this a common problem?