Civ1 locks up / freezes when I press "m"

I'm running Civ1 version 474.04 inside DosBOX 0.74 inside Windows 7 x64.

Sometimes, if I press "m" when it is inappropriate (i.e., if my active setteler is on terrain that it can not "m") my entire game freezes.

This is really annoying. I lose 90% of my Civ1 games this way.

Is there a way to recover the lost game if I have not save recently?
Is there a way to prevent this from happening?

Thanks!

I never encountered this bug before...

Can you prepare a predictable savegame where you know the bug happens in the current turn if you press for M for a specific settler, and hten post it here?
So that others may try to reproduce it.

Can you describe the freeze: can you still mode the Civ mouse pointer? Do you see whether sea/ocean animation continues after freeze? What's you Civ settings (sound, animation, instant advice, etc.) ?