I do get the box appearing with the message,
Windows has detected that audio enhancements for the following devices are causing problems
speakers / HP .... and
Would you like to disable driver enhancements for this devices. I click yes, I get to a control box, but don't know if there is something I'm supposed to do there. I can find in the events tab that "Driver service was added" on January 4, the suspected time of failure.
It seems to me that the exact model of my envy 17 would be immaterial. I have downloaded windows 8.1, but I don't think that is when my sound failed.
I'm pretty sure the hp updates caused this havoc, now I am also suspecting that they caused by camera capability to fail as well.