Try browsing to the '..\Documents\Larian Studios' folder and renaming the 'Divinity Original Sin' subfolder.
This folder contains the saved games, configuration files and a level cache folder. Deleting or renaming it will get the game to recreate it on startup; playing the game from a different Windows user account would effectively do the same thing.
After that, start D:OS and create a new profile, then you can either try starting a new game and save/load, or copy your current saves from the renamed folder to the new profile's savegames folder to check.
