If you have a G3 or G4 upgrade card, try using version 2.2b3 or later of XPostFacto. It permits you to "throttle" (i.e. slow down) the processor for the early part of the boot process, which sometimes helps with this problem. If that doesn't work, here are a few other things you can try. On some machines, you can connect the internal drives to an extra SCSI connector on the motherboard that uses the external bus. Of course, this is not ideal because the external bus is slower on these machines. Another solution that has worked for some users is to change the "Disable Unit Attention" jumper on the drives. This affects the way that the computer "wakes up" drives on the internal bus at boot time. Another thing to double-check would be termination issues, which can vary depending on the other devices attached to each bus (e.g. the internal CD-ROM). Finally, one user reports success installing on a SCSI drive at ID 0, when installing on a driver at ID 1 had failed.