[Rooty]

Hey guys
I installed a new sound card today, and was having the same problem (could hear sounds everywhere except on the internet).
No solutions on t'internet worked, so I decided to mess around with a few settings blindly and crazily.
I found that in Control Panel > Sounds and Audio Devices > Audio
Under the "MIDI music playback" dropdown box, there were two options. I changed to the other, and voila, I could hear Bill Bailey's sweet voice on Youtube once more.

I hope that if you try this it works out for you,

Best of luck

Rooty