Seems to only happen if I have a Activity called Aux.
If I rename it from Aux to something else then it works fine.
The name of the project doesn't seem to matter.
Try doing this:
Create a new project, then add a Activity called Aux then try and run it. You will then see the error. When you rename the Activity to something else and run it, it will then work fine.
There seems to be something about the name Aux as the Activity name.
By the way, it doesn't let you save the project as well.