Window Screen Tearing, After I pPlay a Video or Game

Guys I have a seriosly annoying proble. After I play a game or a video, its everything fine 10-20 minutes, thean like my PC slows down. The video starts tearing(picture and sound aren't standardized), I've scrolling issues, and when I dragg window acrros the screan it is like tearing. But when I minimaze my window its like everything OK. I've tried disabble and enable windows aero,disable/enable hardware acceleration(Adobe flash), reinstalled drivers, tried anything but nothing help. SO IF ANYONE HAVE A SOLUTION PLEASE HELP!!!!!!

Yes, my monitor is 60Hz and all drivers are updated, but still the same. Whats funny when I minaze my window its all fine, but when I maximaze it the video is tearing, or when I'm dragging it across the screen,if it larger the window is tearing if its smaller its not.

My PC temperature is abot 30°C-35°C.

Screen resolution: 1366X768, Refresh rate:60Hz, but its not just a problem with games, after I watch a video too, after 10 mins it starts tering, wand when I dragg my window accros the screen its teairng too