I would shut the machine down, restart, go into bios and turn off the onboard sound and related items (midi, gameport, etc), then boot to SAFE mode, remove any and all sound related drivers (including the gameport) and then shut down and restart to normal mode.

Confirm in control panel multimedia there are not sound devices, confirm in device manager there are no sound devices and shut down again.

Go back into bios, enable your sound devices and reinstall from the drivers from the CD.

If you end up with the same problem, you need to free up some resources - for instance disabling one of the serial (com) ports in bios and/or device manager and then repeat the removal of sound and reinstallation again.