Are you on a dial-up line? If you downloaded the mp3s through one of the sharing systems you may how got a dialer on your system that's trying to dial out and the chirping is your modem (a lot of sharing systems will use your computer's resources to do its work). If you haven't already got some, download some of the anti-spyware programs (Adaware and Spybot Search & Destroy are free - there are threads in the forum with details) and run them.

Mick