I keep my profile on an SMB file share so I can sometimes run Firefox from Windows XP and sometimes from Ubuntu. When it occurs under Ubuntu, I can repair it by running Firefox instead from Windows XP and immediately exiting. When I open it under Ubuntu, the problem is repaired.
The next time it happens, I'll check permissions on the file share to see if I can spot the difference before and after opening under XP.
I have been experiencing the same problem.
I keep my profile on an SMB file share so I can sometimes run Firefox from Windows XP and sometimes from Ubuntu. When it occurs under Ubuntu, I can repair it by running Firefox instead from Windows XP and immediately exiting. When I open it under Ubuntu, the problem is repaired.
The next time it happens, I'll check permissions on the file share to see if I can spot the difference before and after opening under XP.