Cannot Load FreeBSD 6.2 64 bit and maybe other versions as well

[Y Sidhu]

I am a newbie and have gone though past posts and have been looking at the
last couple of weeks of posts go by. I have not seen anything similar to my
problem. I cannot load an OS except under ACPI-Disabled. I can boot into
safe mode, but cannot configure a working network interface. Therefore, I
cannot send in a dmesg output. Here is some data I have gathered:

Details
a.  SuperMicro X7DBR-8+ / X7DBR-I+
b.  Intel 3.2 GHz Xeon dual core dual cpu, K8 class cpu
c.  BIOS - Phoenix (just upgraded to 1.2A from 1.1C) The upgrade has had no
affect on this problem as far as I can tell.
d.  Dual Ethernet - Intel Pro/1000 Network Connection Version 6.2.9. em0 is
IRQ 5 at device 0.0 on pci4. em1 is IRQ 11 at device 0.1 on pci4. Also, when
I am booted in safe mode, in dmesg, there is an entry "em IRQ 10 at device
2.0 on pci5."
e.  SCSI - Adaptec version 4.3. AIC 7902 Ultra 320, PCI-X   ID=7
f.  One 73 GB Seagate Cheetah 10K.7 SCSI hard drive, Model ST3207LC. I have
tested this and another drive out without any media errors. The Adaptec
adapter sees the drive and capacity fine.

g.  When I try to boot normally, the messages scroll by and the system
freezes at:  "waiting 5 seconds for SCSI devices to settle"

h.  When I disable ACPI either under the BIOS's settings or select Disable
ACPI when loading FreeBSD, the system loads but I cannot get the ethernet
interface to come up. ifconfig shows all the right values. I have also used
route delete default and route add default <ip of gateway> - to no avail.
There is a message which pops up saying "em0: watchdog timeout - resetting"
Looking into dmesg output, I see: em0 link state changed to UP and em0 link
state DOWN repeat over and over again.

i.  1 GB ram and have tested it with memtest 86 without any errors.

My Gut
a.  Something is causing a good old fashioned IRQ conflict. I have 1 drive
and 1 cdrom on this machine.
b.  The SCSI ACPI79xx driver is not there or not loading

Hoping
I am looking for a nudge in the right direction.

-- 
Yudhvir Singh Sidhu