HD failure
Art,
The first symptom was probably caused by the disk-validator running and
finding no root block where it thought it should be. After formatting, the
root block will have been in the right place, so no error would occur.
I'm not too sure about the second one, except that I have had a similar
occurrence. I'll try it on a 'binddrivered' partition and see if I still get
it.
-larry