Inventor 2012 - DWG Files Opening in the Wrong Program

The interchangeability of dwg files between AutoCAD and Inventor is a huge advantage, however if you don’t have your default program set correctly for dwg files this can result in the system not knowing whether to start-up Inventor or AutoCAD when opening – this can be extremely frustrating, especially as setting the default program to AutoCAD or Inventor (respectively) is not actually the solution for this and will have no effect! 

If you find yourself in this scenario right click to get the properties of a known AutoCAD dwg file and change ‘Opens with’ to the AutoCAD DWG Launcher as shown.

This launcher is required to differentiate between your dwgs and open the correct program. Repeat this for a known Inventor dwg file. Problem solved!