Vista - graphics card upgrade to GeForce 8800 GT - mce won't work

I have Vista Ultimate with AM2 Socket, AMD 4400+ dual core processor. I
recently upgraded my graphics card from NVIDIA GeForce 7600 GS to NVIDIA
GeForce 8800 GT XXX, and now when I try to watch live TV or record TV or
watch shows recorded before the upgrade I get this error: "Video error;
Files needed to display video are not installed or not working correctly.
Please restart Windows Media Center or restart the computer." I have
installed newest drivers for graphics card and tv tuners. Don't know what
else to try. Would reinstalling Windows help? Any other ideas? Thank you
in advance for any input.

Are you using the default MPEG2 decoder in Vista? If not what decoder are
you using?
Do you have any third party party DVD players on the system such as Nero 7?
I assume that you also can not play a DVD in MD.
Can you play a previously recorded TV show using Media Player instead of MC?
"asphaltsally" <asphaltsally@xxxxxx> wrote in message
news:6962242E-9D08-4F15-88FA-470AB25F2156@xxxxxx

Thank you for your quick anser!
I don't presently have other dvd players on my computer but I have installed
and uninstalled different ones in the past and somewhere along the line that
did cause Windows to stop recognizing my dvd playing hardware, but I can open
the drive in the "computer" menu and click on files on the dvd, so I thought
I had a codec problem but don't know how to fix that either, short of
reinstalling windows. Also, no, I cannot play recorded tv shows in windows
media player either. I get "Windows Media Player cannot play the file. The
Player might not support the file type or might not support the codec that
was used to compress the file."

"JW" wrote:

I have seen reports in the past of installations of other DVD playing
software corrupting the the default MPEG2 decoder software in Vista so that
it is unrepeatable.
I suggest that before reinstalling the Vista release that you have that you
install the now public release of Vista SP1 RC1. I had no trouble installing
it on either of my Vista systems and I am very pleased with the performance
and stability improvements. There is a good chance that it will fix your
current problem and if it does not then consider re-installing the old
release.

"asphaltsally" <asphaltsally@xxxxxx> wrote in message
news:722DCA4F-BAF1-4D65-A51C-0FF8142560ED@xxxxxx

Thanks! I tried SP1 RC1 and it didn't want to install, probably because I
never could get one of the Windows Mail updates from a while ago to install.
So I'm reinstalling Windows. But I did install SP1 RC1 on my other computers
and they're running great!

"JW" wrote: