I just joined to answer the above question, as I saw that people were still struggling with this problem. It was while reading something in the original thread that gave me the insight to dig a little deeper.
My issue was that I connect my laptop to my TV using a USB to HDMI box. All of today I have been playing with software trying to get my integrated webcam to work on my Dell Inspiron 1545, only to find that it was not working owing to a loose cable. But this also became the cause of my sound problem.
I noticed that the drivers for the sound output for my speaker icon for my tv were not correct, mine had a creative .inf as the main driver which could not be right, and seemed to coincide with software that I had installed earlier in the day. I had uninstalled and reinstalled the Viewspan software but this had not worked. So I went to device manager, uninstalled the device from there, and then my system re-installed the correct driver and my sound was back!
Hope that helps someone!