Prior to installing the update to ColorMunki Photo, v1.2.0 you may need to remove the existing software from your system.  
1.       Unplug the ColorMunki Photo device
2.       Navigate to Applications and drag the ColorMunki Photo folder to the trash bin
3.       Empty the trash
4.       Reboot the computer
5.       Install ColorMunki Photo 1.2.0 (link below if needed)
6.       Reboot the computer, plug in the ColorMunki device, and open ColorMunki Photo 1.2.0 to test.

Link to ColorMunki Photo 1.2.0 (if needed): 
http://xritephoto.com/ph_product_overview.aspx?ID=1115&Action=Support&SoftwareID=1499