Appears I've solved this problem
and the solution wasn't so hard. Because
this is my only DDR board, I never had the chance to swap the memory out. But,
(to play the Q4 demo, *cough*) I bought another stick of 256 DDR266, and had
been using it for a few weeks when it occured to me to pull out the old stick.
Well, the old stick had DDR400 written on it! This was news to me as sisoft
sandra had said it was DDR266. Perhaps this is a faulty stick and someone at
Compaq thought would work ok at a lower speed, which I guess it did, except it
also had problems at boot up. This is still a ~little~ unusual as I had already
tried to manually specify the DDR speed rather than have the bios ask the
memory for it's rated speed.