micropolis - shared memory extension error

[Patrick Wiseman <pwiseman@gmail.com>]

Hello:

I just installed micropolis (the GPL-licensed version of SimCity), but
when I invoke it, it reports 'Darn, X display ":0" doesn't support the
shared memory extension.'  Then it just sits there, frozen and
unresponsive.  xdpyinfo reports that MIT-SHM, which I understand IS
the shared memory extension, is among the extensions in my X server.
Is there something I need to do to activate the extension?

Patrick