Can anyone tell me what's going on: This ultra high pitched noise started emanating from my computer a couple days ago... Kinda like the noise tube TVs make when they're on, just on the limits of what you can hear... It's not overly loud, but it cuts in and out. It's really irregular, lasting anywhere from 1-5 seconds... I tried to pinpoint where it's coming from, but no luck... I know it's not the fan, that's about it... Help?