shutdown won't shutdown

[jwyman <jwyman@personainternet.com>]

Hi.  Nothing will seem to poweroff my PC.  I have tried various 
commands, all with the same results.  shutdown -h now 
powerdown
halt
$ su -c '/sbin/halt'
Here's what happens.  Everything happens as it should, meaning, the 
local filesystems get unmounted, the swap gets deactivated, the network 
interfaces get deconfigured.  In short, all the normal processes get 
"done".  Then the screen says, Power Down, but power is still running 
through the PC.  My mouse is still lit up, the cooling fan is still 
running, the monitor is still on, etc.  If I was to hit ctl-alt-del, it 
would reboot.  So what I have to do is unplug the PC which is tedious at 
best.  I haven't the slightest clue how to fix this one.  Any help is 
greatly appreciated.  Thanks
(using sarge, ker 2.4)

John