Have got some more pcs with Intel board DG33BU. These are the same model
board as a recent purchase for which Zen works OK. I can't see a
revision number on the newer boards.

PXE boot Linux stops just after 'Starting hardware detection'

always get:
udevd-event[3443]: create_node: symlink(../../sda, etc)
failed:File exists

now get as well, twice, and then hangs with no keyboard response:
udevd-event[3878]: wait_for_sysfs: waiting for

What could be the difference between these and the other recent purchase?

Any advice would be greatly appreciated.

Regards Warren