The game doesn't support a windowed mode, though some people have been able to get it running in a window using third party programs.
Try running the configuration program, hit the reset button, then set the resolution again. If that doesn't get the game to load properly after you click Apply $ Close, try switching to Software mode rather than Direct3D.
Try the Windows 8 Performance "Patch"
(works in Win 7 and 10, as well); that can help with some startup crashes.
You can manually zip or copy saves from the '..\Divine Divinity\Savegames' install folder. If you have a lot of saves, 7-Zip
can get significantly better compression with the .7z format than zip.