It sounds like there was a corrupt file during the install. Check the '
..\Divine Divinity\Run\error.txt' file and see if anything is listed. I don't know if the installer will update that file or just the program, but it can't hurt to look.
Try re-installing the game; un-install, re-boot, shut down all non essential programs (especially anti-virus), delete the folder Divinity was installed to if it is still there, re-install the game, perhaps start the game and see if you can go up the stairs, re-boot, shut down all non essential programs, install the
patch, re-boot, shut down all non essential programs, start the game. This procedure is a bit over-cautious, but the best way to avoid install problems.
On the off chance that something fouled up the very first time you ran the game, you could try deleting all of the files in the '
..\Divine Divinity\Run\Dynamic' folder before re-installing.
This folder is used as a cache for the game. Files are created / copied there from the save game folder when you load, and written / copied from that folder when you save a game. The files will be re-created as required the next time you start the game. If there was a corrupt file in that folder, deleting the files should fix the problem.
BTW a couple people have ran into this problem with a hatch or cave entrance; the sound effect would play, but they would not actually move.
If that doesn't help, see
Problem with start uphaving problems installing
