sound applet often shows zero volume after loudness change with keys

[unggnu]

Binary package hint: gnome-control-center

Sound applet often shows zero volume after loudness change with the volume keys. The sound isn't actually muted the bar is just gone. If I change loudness again the bar is shown like before. This happens every time after two to four volume changes in one direction.
I am using fresh installed Hardy with all current updates and deactivated compiz but it even happens with compiz. I have two audio devices but if connected only the Audigy2 is used. The volume keys change the Master controller. Afaik this happens with only one connected sound card too but I am going to recheck it soon.

Audio device: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) High Definition Audio Controller (rev 03)
Multimedia audio controller: Creative Labs SB0400 Audigy2 Value