Comment 1 for bug 135183

I seem to have fixed this by following one of the procedures at:

http://thinkwiki.org/wiki/Installing_Ubuntu_7.04_%28Feisty_Fawn%29_on_a_ThinkPad_T61#ALSA_driver_update_.28hard_fix.2C_recommended_for_advanced_users.29

This itself references a page discussing a similar problem with a Fedora installation:

http://forums.fedoraforum.org/showthread.php?t=159516&page=1&pp=15

I used to procedure of recompiling the alsa driver with a patch_analog.c file provided by the author of the page above, and adding a line to the options file in /etc/modprove.d/.