I've got a XP Media Center pc on a Gigabyte motherboard. It's been
running fine for a year. Recently it started beeping (from the
motherboard speaker) about every 4 seconds. If I boot into safe mode
there is no beeping. If I boot w/ MSCONFIG and disable startup items I
have the beeping. I ran memtest and did not find any errors.

Does anyone have an idea what this might be or where else to look?

Thanks.