sound errors need help cant play movies

[ferris-83]

I am running a custom built computer. Its a 3.2 gig asus p4p800 with 1.75 gig ddr ram and 128 meg geforce 6200 card. I had no problems for the longest time dont even remember where the problem stated. I still have sound with most applications exept the majority of movies that i watch have to be watched with media player classic as i get an error C00D11B1 with my media player 11. also i have noticed the videos that will play on player 11 i am able to see a thumbnail pic of in my movie folder the one which display no pic will only open in classic also the one which display no clip will not open in my power director 6 for burning while the one withthumbnail pics will. I am so frusterated been tryuing to fix this for months. I have onboard soundmax audio for which i haeupdated and reinstalled driverrs for manytimes even put in a creative labs sound card and changed that to my default sound to no avail. am i getting incorrect error is it some other problem please help. i am not a noob just encountering something new