Media Player maxing out my CPU at 100%

Hi I am running Media Player V9 with any patches that
Windows update may have loaded. Sometimes when I play
video or always when I play larger Mp3s, after a period of
time (1 -10 minutes), I see my CPU utilization jump to
100% If I can actually get the system to respond, can
close media player, the CPU will drop down to 1-2%
again. If I can't get the system to respond, sometimes I
have to to a hard power off. I'm perplexed is this a
bug in Media Player, an incompatability with my sound card
(Asus P4B533 with embedded sound), or a bad mother
board/BPU. I've replaced all the other components to
trouble shoot it down to this. The bios and the drivers
for the motherboard/embedded sound card are the latest.

Thanks Doug