Sound broken in Ubuntu 12.04

Dell Precision 8500 with Dell's OEM SoundBlaster (driver emu10k1x). Sound stopped working at all in Ubuntu 12.04, after initially failing when trying to play some Flash videos. Works fine on Windows and in Ubuntu 10.04. Tried suggestions from https://help.ubuntu.com/community/SoundTroubleshootingProcedure, no luck. Rolled back with ppa-purge. I get these error messages about alsa in syslog, mentioning a bug in the driver:

Jan 6 22:45:49 DellHome rtkit-daemon[1867]: Supervising 2 threads of 1 processes of 1 users.
Jan 6 22:45:49 DellHome pulseaudio[1865]: [alsa-sink] alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write!
Jan 6 22:45:49 DellHome pulseaudio[1865]: [alsa-sink] alsa-sink.c: Most likely this is a bug in the ALSA driver 'snd_emu10k1x'. Please report this issue to the ALSA developers.
Jan 6 22:45:49 DellHome pulseaudio[1865]: [alsa-sink] alsa-sink.c: We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail() returned 0 or another value < min_avail.
Jan 6 22:45:49 DellHome rtkit-daemon[1867]: Successfully made thread 1878 of process 1865 (n/a) owned by '1000' RT at priority 5.
Jan 6 22:45:49 DellHome rtkit-daemon[1867]: Supervising 3 threads of 1 processes of 1 users.

...

Jan 6 22:49:51 DellHome acvpnagent[1247]: Function: tableCallbackHandler File: RouteMgr.cpp Line: 1694 Invoked Function: recv Return Code: 11 (0x0000000B) Description: unknown
Jan 6 22:50:10 DellHome pulseaudio[2222]: [pulseaudio] main.c: User-configured server at {99e01578939dbb3d4a56c3ab0000000d}unix:/home/oscar/.pulse/99e01578939dbb3d4a56c3ab0000000d-runtime/native, which appears to be local. Probing deeper.
Jan 6 22:50:10 DellHome rtkit-daemon[1867]: Successfully made thread 2225 of process 2225 (n/a) owned by '1000' high priority at nice level -11.
Jan 6 22:50:10 DellHome rtkit-daemon[1867]: Supervising 1 threads of 1 processes of 1 users.
Jan 6 22:50:10 DellHome pulseaudio[2225]: [pulseaudio] pid.c: Stale PID file, overwriting.
Jan 6 22:50:10 DellHome rtkit-daemon[1867]: Successfully made thread 2226 of process 2225 (n/a) owned by '1000' RT at priority 5.
Jan 6 22:50:10 DellHome rtkit-daemon[1867]: Supervising 2 threads of 1 processes of 1 users.
Jan 6 22:50:10 DellHome rtkit-daemon[1867]: Successfully made thread 2227 of process 2225 (n/a) owned by '1000' RT at priority 5.
Jan 6 22:50:10 DellHome rtkit-daemon[1867]: Supervising 3 threads of 1 processes of 1 users.
Jan 6 22:50:10 DellHome pulseaudio[2225]: [alsa-sink] alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write!
Jan 6 22:50:10 DellHome pulseaudio[2225]: [alsa-sink] alsa-sink.c: Most likely this is a bug in the ALSA driver 'snd_emu10k1x'. Please report this issue to the ALSA developers.
Jan 6 22:50:10 DellHome pulseaudio[2225]: [alsa-sink] alsa-sink.c: We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail() returned 0 or another value < min_avail.
Jan 6 22:50:21 DellHome acvpnagent[1247]: Function: tableCallbackHandler File: RouteMgr.cpp Line: 1694 Invoked Function: recv Return Code: 11 (0x0000000B) Description: unknown