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.
If that doesn't help, try starting a new game, run around a bit and see if the map works properly. If a new game works but your latest save does not, it may be a problem in the saves themselves. If neither work, it may be a problem with Divinity, in which case a clean re-install might help. For details see;
Troubleshooting Tips (& manual install procedure)