Hey, Martinimus!
This crash appears to be related to a cinematic crash bug.
Navigate to your Documents/Warcraft III folder and open War3Preferences.txt. Locate the seenintromovie=1 line and make sure a 1 is listed next to it. Locate the windowmode=0 line and make sure a 0 is listed next to it. Launch the game and please tell me if the game still crashes.
Thanks!