With Hardy Heron, my sound worked great. However, once I upgraded to
Ibex, sound is played for only 1 session. After I let my system sleep
or hibernate the sound is gone (on Gnome and KDE)

This is what Linux says my device is when I run lspci:
Audio device: Intel Corporation 82801G (ICH7 Family) High Definition
Audio Controller (rev 02)

This didn't occur on my Hardy system. Anybody else having this
problem?