weird constant hissing sound coming from one speaker

["H. S." <greatexcalibur@yahoo.com>]

Hi,

Yesterday, one of the users logged into a KDE session after a long time. 
As soon as the peripherals started, an error popped up on screen 
indicating an error and the window also had a backtrace tab.

Since that time there is a constant hissing noise coming from the left 
speaker. Logging the user out and then back in does not work. I also 
rebooted the machine and the sound started again (near the point where 
lp0 message comes up during the boot process). I logged in gnome, sound 
still there, I logged in KDE sound still. While logging into KDE I do 
get the initial login music. I also tried killing "kill -TERM" artsd, 
but that also had  no effect on the hissing sound (it is similar what 
you get on an FM radio when you are not tuned to any channed; the white 
noise).

I am running 2.6.7 kernel and the sound card(as lspci shows) is:
0000:02:0c.0 Multimedia audio controller: Ensoniq 5880 AudioPCI (rev 02)

I guess this is a difficult one and I haven't been able to give more 
info (I am not sure where to start). My apologies. But if somebody could 
get me started in the right directoin, I can investigate further what 
could be wrong.

thanks,
->HS