it's screen tearing, and on an LCD it's very noticeable sometimes when the ms response time is higher up.
try enabling Vsync to see if it helps
thanks mate i didnt know what vsync was, i had to turn it on at the control panel to get it to work. i was trying in the games before but it did nothing cause it was turned off at the control panel. i certainley helped get rid of that obnoxious tearing, not totaly but very close.
life saver mate, cheers