gnome-shell won't start for a specific user

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http://forums.fedoraforum.org – hi to all, since one day, i can't start gnome-shell for my main user, but when i switched to fallback mode,the user can login. I've create a new use and i can open sessions with gnome-shell using this user how can i solve this problem? is there a way to reset gnome-shell for one user? i get this message when i tried to connect with my main user: thanks in advance for your help. ps:sorry for the poor english (HowTos)