Firstly: do you have the latest patch? 1.45 loaded?
AFAIK, the patch fixes the monsters that doesnt attack.
If that is not the case, then try this:
Try deleting the files in the dynamic folders;
'..\Beyond Divinity\Acts\Act1\Dynamic', '..\Beyond Divinity\Acts\Act2\Dynamic', etc.
These folders are used as a cache for the game. Files are created / copied there from the save game folder when you load, and written / copied to those folders when you save a game. The files will be re-created as required the next time you start Beyond Divinity. If there was a corrupt file in those folders, deleting the files should fix the problem.
As for the IMP-Hero quest, thats a known bug. Leave your DK at the edge of the town and then use our hero to go talk to the imp. This By-passes the problem. If not, Exit to the battlefields and then come back.
