wierd problems playing videos

When i try and play some videos in vlc, media player original or windows media player i get a bunch of lines on the right hand side of the screen. they take up maybe 1/6th of the screen and are normally green, sometimes static and sometimes flickering.
This started a couple of months ago but i have no idea why as i changed nothing.
There doesnt seem to be any pattern to when it happens and normally just using a different media player fixes the problem, but its annoying.
Has anyone got any idea why this could be?
cheers
Answer #1
Perhaps your codecs are corrupted. It has occurred on one of my PCs before.
Uninstall whatever ones you have, and then install the K-Lite Codec Pack, available for free.
Answer #2
cheers for the reply, not sure that its what made the difference but the k lite codec pack i had installed before was ancient so i installed the new one.
Also reduced my graphics card video acceleration so hopefully it wont have an adverse affects but it works now