iMac- volume slider doesn't effect sound volume

[steve]

In order to adjust sound on my iMac I have to use the volume settings
and adjust the speaker levels. The volume control applet and the volume
sliders in the settings don't effect the volume. I wish it would because
if you listen to anything, you want quick access to volume control. This
problem seems to be affecting many Linux PPC users. Has anyone ever
solved this?

steve