I am having problems playing back some AVI (divx encoded) files in Windows Media Center 7.  For some reason, I can playback most of all of my other video files except for a select few.  When I try to play the files in Windows Media Player, there is no sound. 
When I try to play back the same file in Windows Media Center 7, the file is instantly rejected and I cannot play it at all.

I then installed the Divx codec from divx.com.  This seems to solve the problem, but the problem is my Rew, Fwd, Replay, and Skip functions do not work as well as they did when I had a plain vanilla install.

 The one thing I did notice as that these suspect AVI files have AC3 encoding for sound as opposed to MP3. 

Any pointers on how I can get things working without sacrificing my Rew, Fwd, Replay and Skip functionality?

Might need to put the AC3 codec onto the system, have a look in the forum root at the Codec Bible, sure it's got the heads up for ya ;)