Epox (my mobo brand) issued a statement about A3D soundcards and the VIA KX-133 chipset having issues when matched together. It apparently is something that cannot be fixed w/ a bios flash and Epox recommended not using A3D based soundcards with their motherboard. Isn't that some crap!
The Epox homepage has more details in the EP 7KXA Support documentation. It seems that when the system is under a heavy load, the signal timing loses synchronization or something. Give it a gander.