Hello,
Sometimes I have noticed that just using /etc/init.d/alsasound start/stop gives the "in use" errors, but you might try
$ /sbin/service alsasound stop
then
$ /sbin/service alsasound start
then go into
$ alsamixer
and see if there are more sliders (specifically MASTER/PCM)
then if you crank the vol way up you should get the test sound in
$ system-config-soundcard