Never a problem -- now Dom2 crashes to desktop

[tinkthank]

Argh, I've never had a problem before
Today I tried hosting a small MP game on my standard win98 machine, and dom2 sort of hung during the hosting process; after 10 mins or so (about 15-30 seconds would have been normal) I had to reboot. A few tries, but no luck: once launching the .exe, it crashed to desktop.
So I just reinstalled it, first uninstalling.
Launched, looked ok. So I quit, and patched.
Relaunched, it crashed to desktop. Reboot, and it didnt launch at all, sort of hung in a black screen, and when I used the task manager to finally shut it down, my graphics were kinds of screwy (still stuck on really low).
Reboot, it crashes to desktop.
Does anyone know what this is and what I can do? I am a computer idiot, so if you could help me out in English, that would be great.
thanks much