Further news.
I am able to produce the same problem within sysinst and a partially
installed system.  The problem is manifesting within the esp driver which
reports a string "invalid state 6" and then attempts to reset the scsi bus.
This repeats multiple times and eventually appears to suceed, but once this
has happened it is very easy to trigger again and the kernel becomes
unstable.

The drive is internal and according to all the info I can find should not
need termination in a Quadra 650 (automatic). Setting the termination
jumpers makes no difference.

This drive is MUCH faster than my previous ones, is that significant?
Has anyone else had success with one of these 18.3Gig drives?
Does anyone know about the jumper settings for WD scsi drives?

Cheers
Richard