Reboots at first power-on

Hi, I have a pair of machines I cannot get ES2009 to install on. They are
Dell's Optiplex 755 and 760. On first boot they get past loading some
drivers (I see that via the /sos in boot.ini) and get to the first
blue-screen where the line "Boot loggibng enabled' is displayed then they
reboot themselves.

There's no FBA or bootlog cerated on the disk.

I've built plenty of other working inmages on other Optiplex machines like
the 620 and 960 but these two have never worked.

Any ideas on debugging this?

I thought to build a "Debug" version of my image and attach the debugger but
selecting a "Debug" build results in an image that has no NTLOADER.