why is audiodg.exe interfering with power management?

I have an Intel Core i3-370M 2.40Ghz, ruing Windows 7, that is stuck at 2.4ghz. Months ago, the computer was almost completely silent. Today, the clock multiplier is stuck at x18 and the fan runs constantly. Nothing is When idle, the computer uses 0% - 1% CPU.

I discovered that if "end task" on audiodg.exe, that the CPU multiplier drops to x7 for about 10 seconds, then audiodg.exe restarts and the multiplier goes back up. If I stop the "Windows Audio" service, audiodg.exe stops for good and the problem goes away.

I don't know when the problem actually started. I have had the computer for several years, and it is my Netflix streaming box and DVD player, so it is almost completely bare except for whatever Windows updates it gets.

What can I do?