If you do a search of the forums, I think there are quite a few posts out there that discuss this. I think how I fixed my issue was by going out and downloading the drivers directly from the Realtek site. If you do a google search for Realtek Driver, you will find the downloads easily.
Some people have said to switch the setting from 2.1 to 5.1 speaker settings and that has fixed it for them. I think its something you have to play around with to see what works for you.