This bug is a gateway to a whole load of yak shaving. You open a layer diagram in Visual Studio 2013, drag an item from your solution explorer (like you have done a hundred times before) and *bang* Visual Studio crashes. You retry and get exactly the same result.
This may not be the answer for everyone, but it was the answer for me – and I suspect will be the answer for a number of people in the future who would like to avoid the elongated process I undertook to discover it.
Layer diagrams and WiX projects won’t play nicely together.
If you have a WiX project in your solution, it is probably causing the crash when you drag items onto your layer diagram.
The fix is simple: right-click on the WiX project and select “Unload project”. You can now safely do your diagramming. Once you are done, you can reload the WiX project and carry on as normal.