Stuck on white error screen

Hi,

I have just installed openSUSE 13.1 then i ran the update, after that the system asked me to restart which I did, now the OS is stuck in a white screen saying "Oh no! Something has gone wrong. A problem has occurred and the system can't recover. Please log out and try again". There is a Log out button but it doesn't work and I also left it like that for 1 hour and nothing happened. What can i do???

Thanks,