A while ago, a friend of mine put together a computer for me. Wasn't until just now that I tried to watch a DVD on it (yes, it's an actual DVD, nothing burned) and I got the following error message:

Windows Media Player cannot play the DVD because a compatible DVD decoder is not installed on your computer.

Any idea on what this is, or where I can obtain it by chance?
Quote by Meths

I fucking hate white people. Nobody is destroying "your way of life". They are trying to destroy your country but that's a different matter...

divx or xvid are free wmp compatible decoders, you have to download the full divx bundle (comes with loads of useless stuff) but you can choose which parts to install.