try reinstalling or update your sound card drivers.
try uninstalling your cd drive via device manager and restart the computer.window will find it again and install the driver for it automatically.
try moving your soundcard to another pci slot(as far away from your graphics card as possible)and one that is not irq shared with another device.
try either enabling or disabling DMA for your drive.if its enabled try PIO if its already using pio then try dma.control panel/system/hardware/device manager/ide ata ataip controllers/secondary ide/right click/properties/advanced settings.
try a driver update for your motherboard chipset.
try lowering hardware acceleration for you graphics card as this can sometimes give this effect with sound.for ati cards control panel/display/settings/advanced/troubleshoot.not sure about path for nvidia cards etc.