Boot ISO from the 6.5.2 works on some GX620's, and crashes after loading in
manual mode (auto mode isn't used here). After crashing, it prompts me with
a character-based menu to continue installing linux, eject cd, etc. It as
if the Zenworks pieces vanished!

I can't pinpoint what's causing some to work and some not to work. Some
have ATI cards, some do not. Some are set to Normal mode, some are not.
All are imaged from the same physical network connection (our "lab") so
differences in wiring/duplexing are not a factor. Almost all have A03 BIOS