If you see the error "Colormunki has encountered a measurement problem. Please check to be sure that ColorMunki is properly mounted," it is possible that something has blocked the ColorMunki optics from having a clear view of your monitor display.
Make sure that the instrument is positioned flat against on the screen
Make sure that the computer cursor or your on-screen display is not positioned behind the ColorMunki instrument
Reset your monitor to factory defaults and begin your calibration again.