Media Player 11/ Windows Media Ceter player plays videos too fast

Hi,

I have XP Media Center on a Dell XPS 400 with a two tuner ATI Radeon X600
256MB HyperMemory and Radeon X600 256MB HyperMemory Secondary video card with
Hauppauge WinTV PVR PCII (23xxx) (Tuner 1) and (Tuner 2) sound card.

Both media players (MP 11 & Media Center) have a recurring tendency to play
videos 2-3 times faster than normal. After 1-2 restarts of the computer, it
often returns to normal, but doesn't last long. Very soon both players start
playing videos way too fast. There is also no audio when this happens. Many
others have trouble with accelerated sound, but I have no sound. Just a
super fast video playback no matter the source (DVD, MPEG, WMV, FLV, AVI
file, youtube videos, ect.) Adjusting the Hardware Acceleration tab does
nothing. What is going on? How do I fix this problem so it doesn't happen
anymore? Very frustrating!