HD Prevents Restarts

[ovalking]

I've got this Quantum Fireball SCSI drive, and it works fine... until you restart.
Then it hangs with just a grey screen and won't boot.
Starting from a powered down state is fine - it's just 'warm' restarts that don't work - you have to shutdown before you can get it to reboot again.
Behaviour is the same in a 7500/8600/9500. Makes no difference if you boot off this drive or another.
Disk utilities find nothing wrong.

What could cause this odd behaviour?

Thanks, G.

[devils_advisor]

Spin up/down time, power cause this.

[GaryN]

I'm not an expert in old Mac startup sequences, but I do know that normally, when you start up, the system polls all of the ports to see what's connected and such. From what you say, it would seem that your Quantum will not respond to the system on that level again, once it's been initialized. So it has to power-off and back on to "reset"… Yes, that's vague, but like I said, what the hell do I know?

All we do know is that it's the HDD and NOT the computer, since it behaves the same in different systems.
Does it work properly if you power off and immediately power on again? That would seem to confirm something is resetting in the HDD. BUT, when you say "Makes no difference if you boot off this drive or another", do you mean the computer still hangs just because the Quantum is connected? Is that with another drive before or after the Quantum in the SCSI chain?

This sounds like a job for SuperMacTron…