I have windows media player 11 and vlc. I also have the k-lite codec pack. When i try to play .avi and .mpg (i havent tried anything else). The video is in black and white for both players. The sounds works but its black and white. I tried installing all the available options in the k-lite pack and installing each codec indivudually but it still turns out black and white.
Try uninstalling WMP 11 and VLC, then reinstalling VLC. Use AutoGK to determine what codecs you need e.g. xvid and divx. I wouldn't install WMP anything unless you know for sure you have Microsoft DRMed media and you absolutely need it. Even then I'd only go with WMP 9, no higher. Also uninstalled K-lite Codec Pack. Some people say you shouldn't use codec packs and that they can really screw up you system, but I KNOW the last thing you should do is use ALL OPTIONS. If at all possible, use a restore point to get back to before the codec pack was installed.