Ok, so I've got a B&W G3 with Jaguar freshly installed on it that stops booting at the gray apple screen. There is no spinning indicator when it reaches this screen and with the computer open I see no activity on either IDE channel. I've tried swapping memory and the machine is a bit finicky with what it will take. Some memory that works in other machines will cause this machine to not sync video after the "bong." I've tried doing a PMU reset to no avail and I zapped the pram with the same result. The thing that really gets me is that the machine will boot just fine from: OS 9, OS 9 install media and OS X install media.
I'm running out of ideas so if anyone has anything else I could try I'd be very grateful.