I tried the method you linked to but I am unable to delete/remove/rename the 'Divinity Original Sin' folder in Documents\Larian Studios. It keeps reappearing. If I shut down Steam and then delete the folder, it gets recreated with my old saved games/profile as soon as Steam starts up again (note, when _Steam_ starts up, not even the game).
Is Steam doing some sort of saved game backup which is preventing me from removing that directory? I also noticed that the folder and all its contents are marked read-only. However, I am unable to change that. Unchecking read-only doesn't seem to have any effect.
Finally, I also tried uninstalling the game, deleting the folder in Documents\Larian Studios, and then re-installing. But that didn't help either. The combat dialogue window is still messed up.
Thanks in advance.