I installed M&M7 to my new machine from a "Sold out" box (always worked before, not with XP though), tried to run it,
naturally got a GPF, tried to run it w/o hardware
acceleration, and it ran OK. THEN I exited and started
fumbling with parameters, doing stuff recommended by
various sites (setting Win compatibility mode, installing
Microsoft Windows Application Compatibility Kit, even
trying the MM7.EXE replacement that was posted here
some threads below...)

At some point, I realized that MM7 no longer even tells
me anything when I run it. I rebooted, but nothing
changed. I deleted MM7 directory and reinstalled, but
STILL I got nothing when running MM7 (not even a prompt
for disk 2). I deleted MM7 directory AND the registry AND
the 3DO folder, and reinstalled. It still does not work.