The system hanging right after the changing root device message usually
indicates a misconfigured IRQ for the controller.  The initial probes 
by most (all?) drivers are done in polled mode, only when mounting the
disk for real does the kernel begin to do interrupt driven I/O and DMA.

Is this system a PCI system?  Is the SCSI controller a PCI board?
If so, make sure the IRQ configured in the PCI bios matches the
IRQ configured for the card.

Also, with PCI, forgetting to enable the slot for "master" in the 
BIOS setup or motherboard jumpers or putting
a bus mastering card in a slave only slot will give simlar symptoms.
The system may not have problems under DOS because some SCSI BIOS
or device drivers don't actually use the DMA or bus mastering features
of the card...sigh, they run in PIO mode under DOS.
-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mark P. Gooderum			   USSnail:  Good Creations
Senior Consultant - Operating Systems Group	     3029 Blackstone Ave. So.
  "Working hard to be hardly working..."	     St. Louis Park, MN 55416
EMail:	     mark@Good.com		   Voice:    (612) 922-3953
Interactive: mark@nirvana.Good.com	   Fax:	     (612) 922-2676
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~