Try following the steps in this article and see if it helps. I didn't understand it either, but Google works wonders:
After following the steps there, I discovered that I didn't have the option to roll back the driver for my Realtek Audio device. If you find that you're stuck there as well, try this:
On the 'Driver' tab in the same Properties window as the 'Roll Back Driver' option, click on 'Update Driver' and see if there's an update that can be applied to the device. I've got mine installing right now...so hopefully that puts an end to things.
Hope this helps! These little things are so frustrating sometimes.