On several of my sparcs (ss5/ss20) running 1.6.x (1.6-1.6T)
I am getting some error messages:

   esp0: invalid state: 6

then

   cannot mount root, error = 79

on bootup.  It then fails to boot.  Interestingly, I put 1.4.3
up on one of these boxes (ss5) and it is running bloody fine.
Is something trashing the fs's on these machines, or what?
I have seen this on 4 machines, now over the course of a few
weeks, and I can't seem to find out exactly what the problem
is.  Could something like this indicate nvrams are failing?
I don't see invalid nvram messages and have not yet lost
the prom boot ethernet id, etc.

Any insights or translations are appreciated.

Thanks

Bob Keys