Booted a system, trying to install Windows 2003 R2 Server.
It hung at, "Setup is loading Windows..." during textmode setup.
This is after it installs all the drivers for the system and is about to prompt for additional information.

Found some stuff in the MSKB; quite the vague KB article:
http://support.microsoft.com/?kbid=234772 (Windows 2000)
Other instances of this article exist - addressing different OSes.

In this case, the drivers for my Adaptec 1210SA HostRAID card (2 port) was the problem.  Only when the driver was loaded did the system freeze.

Rolling back to build 10 of the driver resolved the problem.  Strangely the WHQL signed failed to work!