This happens to me too (with ICH7 family chipset). I also get weird headphone behaviour, where sometimes the headphones refuse to work and sound comes out of the internal speakers no matter what I do.
I suspect that the detection of headphones is somewhat broken, and perhaps the 'no sound' problem is related. Perhaps the sound is directed to the headphone jack, but as line out? -- Sound works sometimes on boot - sometimes not https://launchpad.net/bugs/57455 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
