It sounds like you have audio/gameport integrated on the motherboard... In the absence of a dedicated sound chip, computational intensive applications can easily cause such glitches by taking all CPU resources.

Buy the cheapest sound card you can find and disable on-board sound in BIOS. This should help.

The cheapest, but quite decent card, I could find right now is:
http://www.compgeeks.com/details.asp...=0-0-0-0-aj6u6

Hope this helps!