First your RAM wouldn't do this to you. It'll mess with your head but i don't think itd ever do it that badly.
Make sure you have windows media player 10.
Open windows media player.
Go to view -> enhancements -> play speeds.
Make sure that is normal.
Try this as well, i doubt it but this may help.
Start -> run -> type 'Dxdiag' -> After it loads, go to the display tab -> Make sure at the bottom it says no errors.
Do the same in device manager.
Also, you should try to upgrade your driver for your video card.
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