Thanks, Jim. I don't think so, it tends to happen in the middle of a music track and all my music is mp3 cbr stuff. I do hear what I think is a clicking sound from the computer (not the speakers) a split second before the noise occurs. The click sounds like a disk arm parking. The loud noise in the speakers is not a stutter; it is almost like a nasty warbling hum over the top of music. I occasionally hear what appears to be a similar sound on this computer when MC is not being used. The amplifier is on all the time and connected to the computer, but there is no hum sound when the click occurs if MC is not playing; I have never seen any problem when this clicking sound occurs, except apparently when MC is playing (and it only manifests itself as a brief, loud hum). This is all speculation as to whether the clicking sounds are even the same, but that is my thinking at present.
This probably doesn't help much, but I thought I'd give it a try. Next step may be to kick the computer and otherwise threaten it with bodily harm.