Cannot install onto mpt-driven drive

I just got a new Dell Precision 360 workstation with an LSILogic SCSI
controller:

mpt0: <LSILogic 1030 Ultra4 Adapter> port 0xcd00-0xcdff mem
0xfe780000-0xfe79ffff,0xfe760000-0xfe77ffff irq 10 at device 3.0 on pci2
mpt1: <LSILogic 1030 Ultra4 Adapter> port 0xce00-0xceff mem
0xfe7x0000-0xfe7dffff,0xfe7a0000-0xfe7bffff irq 9 at device 3.1 on pci2

I'm trying to install 5.2.1-RELEASE on this machine, then upgrade it to
RELENG_5.  The controller and 36 GB SCSI harddrive are detected just
fine at boot time, but as soon as I go to write out my partitions to
this drive, I get a timeout:

mpt1: time out on request index = 0xfe sequence = 0x000001a0
mpt: Status 00000001, Mask 00000001, Doorbell 24000000
request state On Chip
SCSI IO Request _at_ 0xcde1fc30
	Chain Offset 0x10
	Msg Flags 0x00
	MsgContext 0x000000fe
	Bus: 0
	TargetID 0
	SenseBufferLength 32
	LUN: 0x0
	Control 0x01000000 WRITE SIMPLEQ
	DataLength 0x00010000
	SenseBufferAddr 0x00391de0
	CDB[0:6] 0a 01 3a 65 80 00
	SE32 0xd6937c30: Addr=0x9aa7000 FlagsLength=0x14001000
	 HOST_TO_IOC
	SE32 0xd6937c38: Addr=0xa128000 FlagsLength=0x94001000
	 HOST_TO_IOC LAST_ELEMENT
	CE32 0xd6937c40: Addr=0x391c48 NxtChn0=0x16 Flags=0x30 Len=0x50
	SE32 0xd6937c48: Addr=0xaa69000 FlagsLength=0x14001000
	 HOST_TO_IOC

This trace continues for a while, but I'm transcribing it from the
screen.  I can certainly do the entire thing if someone is interested. 
I can even set someone up with serial console access if they'd like. 
Also note: this same model controller and drive work in another Dell
Precision machine under -STABLE.   I've tried booting 5.2.1 under normal
sand safe modes with the same result.  I looked in CVS, and there didn't
appear to be any relevant driver changes since 5.2.1-RELEASE.  Hoping
someone can help me out.  Thanks.

Joe

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