If you're using Steam, and the game crashes when you start, please ensure you have the latest version of Steam installed.
To make sure your client is up to date, follow these steps:
1) Open the Steam client
2) Click the 'Steam' option at the top left of the screen
3) Select the 'Check for Steam Client Updates' option
Your Steam Client will then update to the latest version if necessary. If your client was out of date, please try re-loading the game.
Please also ensure any mods installed have been removed before attempting to load the game, as this may also have an impact on stability.