I've done every virus scan I could, have Firefox w/ NoScript, and don't download anything suspicious. I'm 99% sure it's not malware.
Well, anyway in the afternoon anywhere from 5pm to 11pm I start to hear voices coming in and out if my speakers. When I turn the volume up they go away, and when I turn the volume down they get louder. It's actually going on right now and sounds a little bit like a Christian radio show or something. The other night it was all in Spanish, but most nights you can't even understand what the people are saying at all.
I think my speakers are picking up am radio, but I have no idea how.
Are you by any chance using a logitech (X-530) speaker set ? I've got the same issue aswell except that when i can actually understand it my voices are german but most of the time they're ununderstandable. Are you also having some weird plopping sound sometimes ?
I had this same thing happen to me at my old apartment. It is what chaud posted earlier usually from lower frequency stations on the dial. The easy fix is to get a headset, new speakers, or turn the speakers off when not in use. The ferrite ring usually comes built in to or with more high power speaker equipment, but you can usually find one at your local Radio Shack (if they have them in stock, not a common item).