PowerBook won't sleep

[Andrew Main]

For some reason, my PowerBook (G3 FW) never goes to sleep anymore, 
even if left for an hour or more. It's presently set to sleep at 30 
minutes, and to "Put the hard disk to sleep when possible." I've been 
on X.2.1 for over a month, and it used to sleep, until the last week 
or so. The display darkens, but the HD keeps spinning, though I have 
no idea what's keeping it awake.

I tried to find a way to manually spin down the HD, so I could see 
what makes it awaken again, but had no luck; another OS 9 feature 
that seems to have been dropped in X. Does anyone know a way to do 
this, or have a guess why my PB won't sleep on its own?

The PB's insomnia is doubly annoying because the old cmd-shift-zero 
quick sleep method is gone; there appears to be no way to avoid using 
the trackpad/cursor to put the PB to sleep manually. Is there?

Andrew Main