Sounds like an IRQ conflict. Try setting interrupts manually in bios(usually under PnP configuration or integrated peripherals). ie PCI slot 1 use IRQ 11 etc.
If your bios doesn't have this option, move the sound card to a different PCI slot. Check in you bios post information(press pause) to see if both devices are using the same IRQ. Updating sound and video drivers could also fix this as some of the later drivers allow IRQ sharing. You'll probably need to enable ACPI in bios as well.

Good luck!