/dev/dsp ownership/permissions keep changing !

[Greg Hamilton]

I have a group named 'audio'. All users who login locally and might 
need sound are members of the group. I chmod /dev/dsp and /dev/mixer to 
group r/w and chown it to root:audio.

Next time I login it's changed backed to gregh:root and it's only r/w 
for the owner. (gregh is my user name).

There's a whole bunch of other stuff in /dev which is also set this way.

Does anybody have any idea what changes the permissions while I have my 
back turned and why?

Greg