Teensyduino 1.40 does not support Arduino 1.6.11. When you run the Teensyduino installer, the intro screen says which versions of Arduino is supports. You'll need to download one of the supported Arduino versions from Arduino.cc. Extract it in a location you can remember, then run the installer again and select the fresh copy of Arduino.
If you're still getting strange errors, please give us a screenshot of the error. Remember, we can't see your screen, and small details can really matter.