SOLVED: 1st, press CTRL-ALT-DEL. When on the selection screen (with logoff, task manager...), press "Cancel". Now, you will be send back to your desktop. Don't worry about the resolution, it's normal. You will have to, manually, minimize or close each and every open window, be it a folder, Chrome or GOG. Once it's done, go to your start menu bar, and click on the icon of Uprising 2. The game will re-open, but the screen will be black. Again, press CTRL-ALT-DEL, and click again on "Cancel" on the selection screen. Uprising 2 will return to normal, and you can keep playing.