Launch Lightroom from the Start menu or by double-clicking the Lightroom icon.
Lightroom 4.0 crashes at launch | Windows
Lightroom 4.0 crashes during launch on Windows when you try to launch it by double-clicking on an image or right clicking on a file and selecting Open with Adobe Lightroom.
We are aware of this issue and are working on a fix.
In the meantime, you can follow the steps below to avoid this problem: