Squeeze install hangs reading CD drive

[Steve Kleene <skdeb@syrano.acb.uc.edu>]

I'm trying to do a fresh netinst of Squeeze on a new desktop, and it's
hanging in "Select and install software".  I looked at console 4 while it was
hanging and saw 8-line kernel errors like this ad nauseam:

sr 0:0:0:0: [sr0] Sense Key: Medium error [current]
sr 0:0:0:0: [sr0] Add. Sense: Unrecovered read error
sr 0:0:0:0: [sr0] CDB: Read(10): 28 00 00 00 00 1e 00 00 02 00
end_request: I/O error, dev sr0, sector 120
Buffer I/O error on device sr0, logical block 30
Buffer I/O error on device sr0, logical block 31
sr 0:0:0:0: [sr0] Unhandled sense code
sr 0:0:0:0: [sr0] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE

So it's failing to read the CD.  Other possibly useful info:

  The motherboard is an Intel DH55HC, and the CD/DVD drive is a Toshiba
  Samsung DVD Writer Model TS-H663.

  The info file on the CD says
    Debian GNU/Linux 6.0.0 "Squeeze" - Official i386 NETINST Binary-1 \
      20110205-14:34

  With another desktop and CD/DVD drive, I verified the checksums on the CD
  with
    md5sum -c md5sum.txt | grep -v 'OK$'
  I also made a second CD and failed with that.

  If I try to install netinst 5.0.2 with the new desktop and drive, it can't
  find the CD drive.  But a netinst install of 5.0.8 completed successfully.
  I would give up and stick with that if Lenny debian-multimedia weren't
  busted.

  During the failed 6.0.0 install, the CD is successfully read quite a bit
  before it hangs.  I found over 30000 files installed on /dev/sda1 (mounted
  on /target).

I'd appreciate any suggestions on how to get the Squeeze install working.
Thanks.