Tony,

First and foremost, if the power pack is plugged into a surge protector, most are not grounded. Consequently, they produce lots of 60hz interference problems. Try plugging the power pack directly into a grounded outlet. If this doesn't solve your problem, you may have a lousy power pack, which is not at all unusual with laptop computers. You can purchase high-quality power packs that provide pure DC current instead of a mish-mash of DC and AC current. I found this to be a problem with some other equipment I was using. I found high-quality power packs at Radio Shack, and they sold for about $30 if I recall. If this doesn't solve the noise issue, the problem may be within the computer's power supply. If this is the case, there's nothing that I know of that will solve your problem.

Good Luck,

Gary