Vista - Windows Media Player and Media Center not working properly

Whenever I try to play a DVD, .avi, .mpg, etc on Windows Media Player, it
plays the video with no sound and gives me the following error:
Windows Media Player cannot access the file. The file might be in use, you
might not have access to the computer where the file is stored, or your proxy
settings might not be correct.
But I'm on the administrator account, so it's not because I don't have
access, and the file is not in use elsewhere.
Also when I ty to play DVDs on Windows Media Center, I get the following
error:
Video Error-Files needed to display video are not installed or not working
correctly. Please restart Windows Media Center or restart computer.
I have restarted both Media Center AND my computer and the DVDs still won't
play.
The video files used to work on my old computer that ran XP, but they won't
work on Vista.

If you click the Web Help button on WMP's error dialog, what URL does it
take you to? That URL itself should have some useful data. =\

Is this an upgrade to Vista or a new system?

--
Speaking for myself only.
See http://zachd.com/pss/pss.html for some helpful WMP info.
This posting is provided "AS IS" with no warranties, and confers no rights.
--

"Lazy" <Lazy@discussions.microsoft.com> wrote in message
news:B61202D5-A212-412C-B517-48BA22441618@microsoft.com...
> Whenever I try to play a DVD, .avi, .mpg, etc on Windows Media Player, it
> plays the video with no sound and gives me the following error:
> Windows Media Player cannot access the file. The file might be in use, you
> might not have access to the computer where the file is stored, or your
> proxy
> settings might not be correct.
> But I'm on the administrator account, so it's not because I don't have
> access, and the file is not in use elsewhere.
> Also when I ty to play DVDs on Windows Media Center, I get the following
> error:
> Video Error-Files needed to display video are not installed or not working
> correctly. Please restart Windows Media Center or restart computer.
> I have restarted both Media Center AND my computer and the DVDs still
> won't
> play.
> The video files used to work on my old computer that ran XP, but they
> won't
> work on Vista.