Did you have an anti-virus program running, or something, that could possibly have interfered with the patch installation? Maybe you could try re-installing it?
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.
You could use
DAD's item editor (or from
Kiya's site, with description) to turn a crappy belt into the equivalent of your current belt, but without the skill bonus. Hopefully that would at least stop your resistances from dropping further.
Divinity adds the Magic Barrier skill bonus when you learn a level, rather than calculating it each time the game is loaded, so you can boost your resistances back up using
iZakaroN's SaveEditor (also listed at Kiya's site above, with description). Remove the skill points you put into Magic Barrier, then load the game, max Magic Barrier and save. Repeat until your resistances are back to where they should be.