AVI, MPG and WMP Problem

Okay guys, here's my dilema. One day I just went to go watch one of my happy lil movie files when windows media player gives me this error:

Windows Media Player cannot play this file. The file is either corrupt or does not support the format you are trying to play.

0xC00D1199: Cannot play the file

When I know it should play the file (since it's played it many times before). My computer still plays quicktime movies so I'm pretty sure it's a Windows Media Player issue.

Can anyone help me? I'll love you forever and ever!

Edit:
Windows ME
Windows Meida Player 9.0

I dind't download anything either before the problem occured either, it just happened all of a sudden.

 

try the codec pack which is awailable, I was having the same problem, after install the codec everthing seems to be working fine.

Chears

 

Where can I download this codec that you speak of?

 

Well the file types I'm trying to open are:
MPEG, AVI and WMP.

The files do not open in other players such as real media player and quicktime.

I haven't done any compression, defragging or encyrpting.

The files work on other computers though