Contradiction in messages with no indication on what to fix!

How can it say "This device is set up" followed immediately by "Errors were encountered while preparing your device for development". Please check the devices and Simulators Window. I am in the window it tells me to look at. It is pointing me to itself. And it does not give any useful information. How can it be setup if it encountered errors. this is a contradiction! How do I fix the problem if I m not told what it is? I worked Yesterday how can it be prepared one day and not the next? Now my Mac Pro can not even see it.