You could try a clean re-install of the game (uninstall, reboot, make sure there is noting left in the install folder, shut down all non-essential programs and re-install).
A few people had a problem with not being able to switch skill bars, and possibly not have the options to assign hotkeys for that in the Controls list; re-installing fixed the problem, when verifying local files did not identify any corrupt or missing files.
Before that, though, try downloading
this zip and extracting it into your '..\SteamApps\common\Divinity - Original Sin' folder. It contains a small program called
DVDsig and an md5 file created based on my install folder. If you run the program and click on Verify, it will check your install folder and compare it to mine; any differences (aside from DLC or anything system dependant) may help find the problem.