This is usually one of two things.
1. The video driver is not at millions of colors.
2. You deleted a codec.
I can't tell you what codec you need, but you can learn about such at http://www.moviecodec.com
my .wmv/.mpg (all video) files were fine two days ago but now, the colors all messed up. its like theres a white see through "mask" covering the video. it's not windows media player's ( 9 series ) problem because the videos are messed up when i play them on divx. i recently deleted some files i thought were useless. could that be the problem? any ideas. much appreciated. thanks. i use windowsxp.