I have a problem. I have a solution. I have a Mac G3 with a added PCI Card to allow USB devices to be used. I have been running System 9.0.4 for ever, and had no problems. I have several USB devices plugged in to the to PCI card, including a printer, optical mouse, external USB CD Burner (SONY), flashcard reader, etc. When I upgraded to System 9.1 from 9.0.4 I noticed a problem. More often than not, I could not get my Mac to wake from sleep. I had to reboot to get it to come back to life.
I accidently discovered a work around. Seems if I turn off my Sony CD Burner with the power button on the front of it, my mac will ALWAYS wake up. I don't now why this is, but since I don't use the burner much at all, it is no problem keeping it turned off, and this solves the sleeping problem.
Thought you might like to know this.