VideoPlayback lag when full screen

when playing videos on full screen using windows media, VLC and windows media classic it lag so hard. while not in full screen it is smoother but still a bit lag.

same goes to streaming videos on youtube.... lag a tiny bit but when in full screen hardcore lag! unwatchable!


i have uninstalled all codecs ive installed and install just k lite codec pack which reduce the lag efficiently, before i clean up codecs...... non-full screen also lag hard. after i clean 4,5 codecs pack from my system the non-full screen is watchable.


i also tried taking off my graphic card and just use default monitor hole and still the same. how to fix this lag in video playback?