For some reason, on my XP machine and a few others I've seen, if the computer boots up with a CD in the drive, the system calls for a CD-ROM spin up at random times, especially when there was a legitimate call from a program running at the time. I get this a lot when running old Duke Nukem 3D v1.5, which only called the CD to check copyright. Raze is right, though. If it's bothering you, go sound-proofing so other games don't bother you as well.