Mardaneus is casting a spell at that point to freeze Lanilor in place (until you find a way into undo that).
It couldn't hurt to try running the game on a single core, though this isn't a known issue (some people have had random static in the game, which could generally be fixed by running the game on a single core). The easiest way to do this would be to right click on the div.exe file in the Divine Divinity install folder, select Properties, switch to the Compatibility tab and set it to run in Win 9x mode.
You could also try lowering/changing the game resolution, or switch to Software mode rather than Direct3D.
You could try re-installing DirectX 9c and the VC redistributable in the 'support' subfolder of the main install folder.
Try a clean re-install of the game: uninstall, reboot, make sure there is nothing left in the install folder (except maybe your saves, but you haven't gotten far enough to worry much about them), shut down all non-essential programs (especially anti-virus), re-install, start the game and get the update to 1.0062A (as shown in the bottom right corner of the main menu).
