When I go to sleep at night,, approximately 10-15 minutes after my comptuer idles or plays music, the HDD just starts to go nuts and it sounds like it's defragging or something.. as soon as I go move my mouse or anything the sound stops .. I check processes and it's just 99% system idle. i have nothing set to autorun at night, and HD doesn't turn off after time or anything. strange problem and I don't know what's causing it! anyone have any ideas?