Sony PCG-GRX570 laptop, panic on boot w/ 5.1R and -current

I've been trying to install something 5-ish on a Sony PCG-GRX570
laptop.

I started off trying to boot off of the 5.1 release CD, normally,
w/out acpi, and safe.  Every option panic-ed, with essentially the
same message (see below), although it followed a different driver
depending on how it was booted.

Then I installed 4.7 (since I had the CD), cvsup-ed my repository, and
cvs up'ed /usr/src to the 5-current.  I followed the section on moving
from 4 to 5-current in UPDATING to build the world, etc....  I had to
work around a bit of previously reported 4.7/5 weirdness in
/usr/include, but it went w/out any trouble.

When I reached the point where I was supposed to boot the new kernel
in single user mode, the 5-current kernel paniced:

  miibus0: <MII bux> in fxp0
  inphy0: <i82562ET 10/100 media interface> on miibus0
  inphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
  
  
  
  Fatal trap 12: page fault while in kernel mode
  cpuid = 0; apic id = 00
  fault virtual address	= 0x63696d20
  fault code		= supervisor write, page not present
  instruction pointer	= 0x8:0xc0659df3
  stack pointer		= 0x10:0xc0c217ac
  frame pointer		= 0x10:0xc0c217cc
  code segment		= base 0x0, limit 0xfffff, type 0x1b
  			= DPL 0, pres 1, def32 1, gran 1
  processor eflags	= interrupt enabled, resume, IOPL = 0
  current process		= 0 (swapper)
  kernel: type 12 trap, code=0
  Stopped at	ithread_add_handler+0x163:	movl	%ebx,0(%eax)
  db>

I've seen several similar reports in the archives for late last
summer.  The general answer seemed to be that people were having
hardware trouble.  I don't think that is the case in my case, unless
-current is doing something very strange, since the same machine runs
well enough under 4.7 to buildworld and buildkernel, and the same
hardware has been running Suse and Win2000.

How can I help get this solved?

g.