If you open Windows Explorer and browse to the saved game folder (in '
..\Divine Divinity\Run\savegames'), can you open the shot.xxx file in a graphics program (such as the freeware
IrfanView)? These screenshot images are in TGA format.
In Beyond Divinity, enabling anti-aliasing will cause the screenshot previews to be black, but I don't recall anything that will cause that in Divine Divinity. Have you changed the graphics settings in DD, or updated your video card drivers, or something?
Long shot, but try deleting all of the files in the '
..\Divine Divinity\Run\Dynamic' folder.
This folder is used as a cache for the game. Files are created / copied there from the save game folder when you load, and written / copied from that folder when you save a game. The files will be re-created as required the next time you start Divinity. If there was a corrupt file in that folder, deleting the files should fix the problem.