sound stops working after a while in ubuntu 12.10
Solution 1:
remove the .pulse directory and the file called .pulse-cookie in your home folder;
then you need to logout for the change to take effect.
that's the way that I use most of the time.
Good luck.
Solution 2:
had the same problem with no luck, got back to ubuntu 12.04 and everything was working fine
Solution 3:
I used alsamixer and changed Auto-Mute Mode to Disabled