Kernel 3.15 rc8 not working!!

[stamper]

Strange but today kernel 3.15 is out and it works.

After 2 times of booting and 1 problem, INVALID MIT-MAGIC-COOKIE-1 KEY.
I solved it with the follow commands :
sudo apt-get install --reinstall xorg
sudo rm /home/username/.XAuthority*
sudo rm /opt/.X0-lock

Then restart and it works.