error downloading codec - MPEG

When I tries to open my mpeg file, it came out with the message 'error downloading codec' and then it showed a black screen but there’s the sound. It works fine some other mpegs. I tried to download new codecs but I don’t know which is the correct one. What should I do?

I am using Window Media Player 10 at the moment.

Chances are the file is an mpeg-2 instead of mpeg-1. I suggest using an alternate player such as videolan (www.videolan.org) or media player classic (www.gabest.org). If you insist on being able to play the file in windows media player, you can get an mpeg-2 decoder as sold by some companies (elecard, lead technologies, bitcontrol, and many other). Installing DVD software (cyberlink powerdvd, windvd, etc) will also let mpeg-2 files play in wmp.