It crashes, or just freezes? It takes a while for the DLC to load, the screen freezes while that is happening, which is normal. if you are playing on the PC and your game is crashing this is the wrong section to be asking for help.
Other than that are you sure your DLC matches the same region as your game? They are not in two different languages? You need the 1.8 patch to play Dragonborn, so if you do not have your game updated you will have to delete the DLC, connect to the internet, get the patch and then download the DLC again. Applying the patch after the DLC will make it unplayable at certain points. You have to download the patch, then the DLC.