i had the very same problem with
kernel 2.4.24 KDE3.2 Fedora Core 1.
the artsd server hogs the sound hard !
as root, when sound is nolonger working type
i bet a program called artsd is using the sound card...
and typing killall artsd will temproerilly fix the problem correct ?
go into control center, and in the sound section, turn off artsd.
this works quite well.
it seems kde3.2 is a little buggy.