G4 Panther Won\'t Sleep-- Bad Display Usb Hub?


In the last few weeks my Mac doesn't sleep; when I press the sleep button, it starts to sleep, then re-awakens after a second or so. I believe I have isolated the problem to the USB hub in the display; if I start up with the display not connected, wait for startup to complete, then press the power button once, by the sound I know it has successfully gone to sleep. Is there any way to verify that this is a hardware problem?
OS10.3.0, or 10.3.7, or 10.3.9 (various re-installs tried without solving the problem); G4, 733 MHz, 896 MB RAM. I have tried Disk Repair, Hardware check CD, TechTools, to no avail. Problem appears right after an Archive and Install, too.
Problem solved!
There is a slow corrosion problem in the display-to-nVidia ADC (sp?) connection. Cleaning the plug with Radio Shack spray-on cleaner fixed the problem. Occasionally it reappears; unplug, wiggle, plug back in and it's gone.
This is supposedly a known problem -- "silver tower insomnia".