I would assume that version is not eligible for the Developer's Cut upgrade.


Did you try rebooting again to see if that was what helped, or it was just a coincidence? Maybe it is random, so if you try a dozen times, or something, maybe it will work again?


One person in the GOG forum reported that setting the game to run on a specific CPU core helped:

Quote
The only thing that I found that worked was setting the multicore affinity to 1 processor manually. I also used a program to set the affinity permanently: ImageCFG. There are others out there that do this, but the one I am used to is ImageCFG.

You could also try disabling multicore in the graphics options.


Do you have access to a different computer you could install the game on? If so, and the game works properly, you can save right away and then transfer that save back to your computer (there is an illusionist in the starting village where you can go through the character creation process again, if you wish).



In XP the saves are in the folder

C:\Documents and Settings\ %username% \Local Settings\Application Data\Divinity 2\Savegames


or in Vista / Win 7

C:\Users\ %username% \AppData\Local\Divinity 2\Savegames


You may need to set Windows Explorer to show hidden files and folders (XP, Vista, Win 7).