So much for my vow not to mess with the server tonight. On a hunch I tried installing an older version of Red Hat with the 2.4 kernel... guess what? No panic! Obviously something funky is going on in ring 0 (and I still strongly suspect the junky old video card). But at least now with an OS installed I can now run diagnostics to make sure that it is in fact the video card that is messing everything up. At the very least this will save me a trip since if there does turn out to be some other hardware problem then I can take the offending piece of hardware in with me tomorrow when I pick up the back-ordered items.