I had the same problem. All of my videos started playing in black and white. I finally noticed that the setting for my Nvidia card got screwed up somehow. It appears the Nvidia settings over ride the WMP settings for color (I did not know this). No matter how I adjusted the WMP color settings it would play in black and white. I have the 91.47 driver. I went to the Nvidia control panel, there you can choose to adjust the "display" settings or the "video and television" settings. For whatever reason my video and telivision settings had gone to the bottom on color and contrast making all my videos play in black and white. I adjusted them back up and I have color again. It makes me mad that it was so simple cause I did a ton of searching on google and some other forums and came up with nothing. I still do not know exactly why the settings changed, but I do know it happened after I installed the SP2 update.