I hope this is something I can fix with the right settings, but I haven't found any other settings that work well yet. I understand that it is due to resolution differences between a 20 yo game vs a modern operating system. This happens if I click off the screen when I run dual monitor set up, if I click the edge of the screen with one monitor, if I leave my computer for long enough for the computer to turn off the screen, and sometimes at random if Windows decides it needs to be minimized for whatever reason. Without any modification of game files, the only nuisance (albeit a big one), is alt-tabbing freezes and turns the screen black for 5 seconds, after that the game can no longer be alt-tabbed back into.
I can't make it bigger, and on the off chance that it's still full screen, it's unresponsive to my input and I have to Alt-F4 and start over. When I play C&C Red Alert 2/Yuri's Revenge, I frequently get a problem in which if the game is minimized (or otherwise not the top window.) and I try to bring it back up, it comes back up as a tiny unresponsive with the sound still playing.