I had something similar until I stumbled across this bug, the top of which there is mention of esd.
$ ps ax|grep esd 8774 ? S 0:00 /usr/NX/bin/nxesd -tcp -nobeeps -port 6000 -bind 127.0.0.1 9482 pts/1 R+ 0:00 grep esd
And sure enough, in my case nxesd (of the Nomachine program) was occupying the sound. (I had the 'enable multimedia support' enabled for nx client connections to foreign servers.)
I had something similar until I stumbled across this bug, the top of which there is mention of esd.
$ ps ax|grep esd
8774 ? S 0:00 /usr/NX/bin/nxesd -tcp -nobeeps -port 6000 -bind 127.0.0.1
9482 pts/1 R+ 0:00 grep esd
And sure enough, in my case nxesd (of the Nomachine program) was occupying the sound.
(I had the 'enable multimedia support' enabled for nx client connections to foreign servers.)