From the original printout:

hda: IC25N030ATCS04-0, ATA DISK drive
hdc: HL-DT-STDVD-ROM GDR8081N, ATAPI CD/DVD-ROM drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
hda: attached ide-disk driver.
hda: host protected area => 1
hda: 58605120 sectors (30006 MB) w/1768KiB Cache, CHS=3648/255/63
ide-cd: passing drive hdc to ide-scsi emulation.
hdc: attached ide-scsi driver.
Partition check:
hda: unknown partition table
ide: late registration of driver.

The last line may be a clue - if the ide-scsi driver is late registering drive hdc, the request for partition information from hda may not be being processed in time - note the ide-scsi driver has identified the hda drive size parameters (5 lines up), so communication is operational, but it seems to be busy with hdc, the CDROM-DVD. Is it possible there is a race condition, with the combination of the hard drive and the CDROM/DVD?

Anybody able to compare the HD and CDROM combinations in Toshibas that work, with those that don't?