During the user “Sensor” calibration, the board cut/edge test failed to perform within its tolerances.  The machine is told to cut a small (0.050″ or so) slice from the notches it puts in the board with the 3/8″ bit.  The board sensor re-reads the slice and checks if the machine cut the proper amount.  If the test cannot get within 0.005″ & 0.003″ in 3 cuts, you get this error.