So in the past 3-4 months I built an HTPC for my girlfriend and myself, and all in all it works pretty well. Every now and then it locks up but for the most part it just runs 24/7 and sits in under the TV. However... when it does lockup and requires a restart, when it boots back up the Realtek drivers are uninstalled... If you shut down the computer (not using the restart option in windows), when you push the power button to turn it back on there will be no Realtek drivers. So you go to install them again, it prompts you to restart, and bingo... sound works fine. We are running Windows 7 and using on-board sound/video with an HDMI cable communicating both signals to the TV. Thus far I have been 100% unsuccessful in finding any solutions online. Does anyone have any ideas? Its really frustrating because this has been a problem right from the get-go. Any help would be appreciated!