Yes, you will be able to use the same saved game. Some of the story fixes in the patch only apply to new games, but the technical fixes, additional quick save, etc will help with games started before installing the patch. I would save under a new name (or make a copy of the saved game folder) before deleting/replacing the world.x1 file, though.
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 you had not been to Verdistis before, a clean install of Divinity may help, after backing up your saved games (just in case). see;
Troubleshooting Tips (& manual install procedure)