5.1-RELEASE hardware detect problem - install stalls

I am attempting to install 5.1-RELEASE.  The following items appear in
the log file.  This section is repeated ~15 times, and then the install
procedure moves on to the "...probing devices ..."  screen and never
moves on from there (of course, never is the limit if my patience ... 30
minutes).

I am using the 5.1-RELEASE-i386-disc1.iso pulled down from a mirror ftp
site today.

First, here's the cut/paste of dmesg for 4.8.  I think it might be
relevant to the hardware configuration with which 5.1 is having problems.

----------------------- start dmesg------------------------------
-----------------------------------------------------------------
FreeBSD 4.8-STABLE #0: Fri Jul 25 10:22:38 PDT 2003
    joe_at_wotan.dubium.com:/usr/src/sys/compile/KERNEL.4
Timecounter "i8254"  frequency 1193182 Hz
CPU: AMD Athlon(tm) XP 1700+ (1471.92-MHz 686-class CPU)
  Origin = "AuthenticAMD"  Id = 0x662  Stepping = 2
  Features=0x383fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE>
  AMD Features=0xc0480000<MP,AMIE,DSP,3DNow!>
real memory  = 268369920 (262080K bytes)

<snip>
atapci0: <VIA 8233 ATA100 controller> port 0xfc00-0xfc0f at device 17.1
on pci0
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
<snip>

ad0: 19470MB <Maxtor 52049U4> [39560/16/63] at ata0-master UDMA66
ad1: 19470MB <QUANTUM FIREBALLP LM20> [39560/16/63] at ata0-slave UDMA66
acd0: CD-RW <PLEXTOR CD-R PX-W1210A> at ata1-master PIO4
acd1: MODE_SENSE_BIG command timeout - resetting
ata1: resetting devices .. done
acd1: CDROM <CD-ROM CDU611-F> at ata1-slave PIO4
Mounting root from ufs:/dev/ad0s2a
cd1 at ata1 bus 0 target 1 lun 0
cd1: <SONY CD-ROM CDU611-F 2.1a> Removable CD-ROM SCSI-0 device
cd1: 16.000MB/s transfers
cd1: cd present [315026 x 2048 byte records]
cd0 at ata1 bus 0 target 0 lun 0
cd0: <PLEXTOR CD-R   PX-W1210A 1.10> Removable CD-ROM SCSI-0 device
cd0: 16.000MB/s transfers
cd0: Attempt to query device size failed: NOT READY, Medium not present -
tray closed
------------------- end dmesg -----------------------------------------
-----------------------------------------------------------------------

I used the verbose logging option to obtain the following information

------------------ start 5.1 install logging ------------------------
---------------------------------------------------------------------

acd0:	<Plextor CDR ....  > at ata1 as master

<snip, the next 7 lines repeat>

acd1:	MODE_SENSE_BIG command timeout - resetting
ata1:	resetting devices ..
ata1:	pre reset mask=03 ostat0=50 ostat2=08
acd0:	ATAPI	14eb
acd1:	ATAPI	14eb
ata1:	after reset mask=03 stat0=00 stat1=00
ata1:	devices=0c












-- 
Joe Sotham
------------
praxis makes Perfect.
        - Meister Eckhart