My problem come's when I try to play from an NTFS partition that I share with my Win7 dual-boot. Every time that I try to open any video file, the system logout. HELP!!!
First of all try if it works after you copy the video file to your linux partition. But IMHO there is a mistake with your X configuration. Try using another X driver (for instance VESA), make a dist-upgrade and re-install your graphic driver. Try using another video player.
Are there messages in .xsession-errors that give you a hint?
Sounds like fglrx and Xv-Bug.