Try checking the following:
-set your hard drive's auto-spin jumper to ON
This will imediately spin up the drive upon power-up.
-go to the CSPPC early-boot-menu and see how the SCSI settings look like.
In here, you can see which SCSI device IDs are operational and which are not. Turn off all unused IDs and turn on only the used ones. Also, tweak with the async/sync settings for your SCSI chain and see how your devices respond to faster/slower settings. You can also do the same with the error retries/delays timings, etc. It all matters and could potentialy make the difference. I've had similar problems like this before. Basically, one device in the SCSI chain could make or break the rules and not let the entire system boot as SOMETHING is not up to its liking.
