Um, never mind about the hopeful comment regarding being able to move the network boot from first in boot order. That seemed to be OK thru multiple test boots including a complete power down/up. But, for whatever reason, the next day the <freezing when Unity started> behavior was consistently back. So I once again moved the netboot to first in the boot order and, several days later, all still seems to be OK.
Um, never mind about the hopeful comment regarding being able to move the network boot from first in boot order. That seemed to be OK thru multiple test boots including a complete power down/up. But, for whatever reason, the next day the <freezing when Unity started> behavior was consistently back. So I once again moved the netboot to first in the boot order and, several days later, all still seems to be OK.