I just helped a co-worker with this issue. After many tries to update the driver, searching for new drivers, etc., we found that there are two audio drivers installed on this model laptop. It may be a conflict causing the issue. The laptop shows the Intel driver as the Audio driver but if you go to Start>Control Panel>Uninstall a Program, you will see the RealTek High Definition Audio Driver installed as well. I uninstalled the RealTek High Definition Audio Driver (it can easily be downloaded again if needed), and the sound started working normally. It's a low-risk fix and worth a try for anyone having the issue. Good luck.