I had this problem on my Q650. What worked for me was installing one
binary package at a time instead of installing the base,X11R6,etc,man
etc... all at once.  I don't have enough technical know-how to tell you
why this works this way for me.  Maybe someone else on the list will
elaborate or correct me if I am misleading you.

Gerald

> I am now to the point where I am trying to install NetBSD current
> snapshots onto a 1.2GB Quantum HD inside of a Centris 650.  When I try to
> install the base or the misc, I get a problem about 80% of the way
> through.
> 
> Error SCSI Read() #5
(snip)