Vista - Video error message C00D11D2

"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."
I'm running Vista Premium and everything is up to date. I cannot play any
video in WMP 11. There is one video saved on my hard drive that it will
play, but nothing else. Not even the sample videos that came with Vista. It
doesn't matter if I save a new video on my hdd or transfer it from another
hdd or stream it off a webpage. I always get that error message.
It's been doing this for over a week now. I've gone through and reset all
the default settings in the player and adjusted the settings to match those
on my other computer, but nothing I do seems to help. The "help" page I get
with the error message is completely worthless
(http://www.microsoft.com/windows/win...alid=80070005).
Is the only way of fixing this to reinstall my os? Any suggestions would be
much appreciated.