Have a look through this thread: http://forums.taleworlds.com/index.php?topic=69797.0 Looks like the most common cause is skipping the into
Other fixes I've seen include running it as admin (right click steam when starting and select run as admin option). Also try tweaking your graphics options.
You can also right click on the game in steam, go to properties, local files and then run the verify game cache check.