NetBSD 5.1/AMD64 SMP/usb(?) related boot hang / UP ide(sata) boot failure

[theo borm <theo_nbusr%borm.org@localhost>]

Dear all,

Because my new workstation doesn't have a CD player, I used a different 
computer to do a brand new install to a harddisk.

This new install fails to boot:
1) SMP enabled: hangs (hard) after  "uhub6 at usb3: vendor 0x1002 OHCI 
root hub, class 9/0, rev 1.00/1.00, addr 1"
2) ACPI disabled: detects 64 PCI busses (?!), and hangs at the same point
3) ACPI and SMP disabled:  displays numerous "wd0d: device fault readinf 
fsbn 0 (wd0 bn0; cn0 tn0 sn0), retrying" and "ixpide0:0:0: recall drive 
fault" errors, and drops to a prompt asking for a root device.

same disk works fine in 2 other computers.
same machine works fine with another OS.
same disk can be read/written without errors in the same computer, on 
the same SATA channel from another OS.

There seem to be two separate problems: SMP related and sata/ide driver 
related.
If necessary, it is no problem to get a different (supported) sata 
controller.
The SMP problem, however, is a show-stopper as having only 1 core 
available from a 48 core 512GB machine sort of defeats its purpose.

how to proceed?

The mainboard is a Supermicro H8QGi-F. If useful, I can provide a  
(linux) dmesg, only it's somewhat bigish (100K+)

with kind regards, Theo