Your Firefox profile cannot be loaded.

I'm using Profile-sync-daemon in order to place my browser's cache in ramdisk at boot, to use the ramdisk during navigation and to replace the cache on the disk during shutdown.
I'm also using ubuntu 13.04 wich is not quiet well de-bugged and sometimes crashes leaving my firefox profile in dead memory. So when I restart the computer and run firefox it says : "Your Firefox profile cannot be loaded. It may be missing or inaccessible."
Just go to /home/uname/.mozilla/firefox and rename your backed-up profile folder abcdefg1.default.backup (you will find its path in the profiles.ini file) to abcdefg1.default
Firefox will start again with an old profile but it works !