|  Then I rebooted... And it did the same thing: graphics 
|  flipped out for one second -- with the top half of the 
|  screen like it lost horizontal sync. But just for a 
|  second. Then it came back to the "Welcome to NetBSD" 
|  graphical login.

  Why don't you check the kdm log file? That's about the
only way to find out what happens. I have no idea where kdm
puts it, xdm writes /var/log/xdm-errors, for example.

	mjl