Problems with sound files for events

[AG <computing.account@googlemail.com>]

Hi

Using GNOME, the volume control has greyed out all options for using a 
"sound theme".  The card is HDA NVidia using the ALSA mixer, but I am 
unable to access any sound files for alerts, etc.

Is there an arcane trick to getting this sorted or is it a problem with 
the sound card.  Other audio files play fine (*.ogg *.mp3 and audio 
CDs), but Kaffeine doesn't play sound either.

Any ideas/ suggestions?

Cheers

AG