slow motion graphics but high frame rate!

I've had my Inspiron 5150, 3.2ghz/512ram/geforce fx 5200 graphics card for 4 months now and the graphics have been working very well on my games.  Just 2 days ago, my graphics started runninng in slow motion.  It would run in slow motion for a while, then it would go away for a few seconds, but then it would come back again.  The same cycle occurs for any graphics/games I run and at every graphics/resolution setting I've tried.  I have the newest nvidia and directx drivers.  I have even tried reformatting my computer to make sure no spyware runs in the background.  I've tried shutting down all programs running in the background, including my anti-vrius and I get the same result.  Does anyone know what is wrong or know of this problem?  Someone told me it was overheating, so I shut off my laptop and let it cool down overnight and I still get the same problems.  Help!