A few days ago, I installed a new video card. I went from the original intel chipset to a geforce 6200. After I installed the card, all of my games worked great and everything was going good. But I am not able to view any videos in windows media player. If I try to run a video, my computer starts to run VERY slow and eventually freezes so I am forced to restart. I uninstalled and reinstalled the drivers but that didnt help. Any ideas on what could be wrong?

Plug your previous videocard again.
Install it drivers.
After it...
Run videos...
Is this slowly and eventually freezes???

Try reinstalling Windows Media Player and Directx.. If there's any available software for the GeForce graphics card, whether or not if its just the drivers, install them all. I know one of them must definately be a control panel for your graphics configuration after you installed that software. I believe it will solve this problem..

Otherwise, read the documents that came with your graphics card..

Do you have to deactivate your onboard card in your bios ? I never had an onboard graphic card so I don't know if that has to be done, but maybe that causes problems...

But if you only got problems with watching videos maybe the zoom player can help you

the problem copuld be that your computetrs ram or system mothrboard cannot keep up with the graphics bus because all graphics cards go through the motherboard through the ram adn backout to the scren so the problem may well be that.
so try and get a memmory upgrade and then see what happens.

Sounds like a software or driver problem to me. And BTW, if you have to disable the onboard VGA to install another card, you will know because you usually won't have video on the new cards' output. I would suggest running DXdiag from the run command on your start menu. To do this go to start menu> run> then type in dxdiag. This will run diagnostics on your DirectX installation.
Keep us up to date when you work this out and good luck!