Yes, now I am able to duplicate this 'freeze' problem.
Open MoI 4
Hide it using the - key in the upper right corner of the screen.
Open another program ... shut it down.
Bring MoI back to full screen by clicking on the MoI icon.
Commands are frozen.
Reduce MoI to part screen. Open it to full screen again.
Now it works.

For me this is intermittent. It does not happen each time I follow the same routine.

cheers,
eric