On a new MacBook Pro, I have just loaded the latest version of OS X 10.10.3 (released Apr. 16). Now, when I click on the Messages icon, the computer hangs, with the colour pinwheel spinning. Nothing is selectable with the mouse or keyboard. I can only shut it down by holding the Power button for several seconds. Upon reboot, if I click the Messages icon, the computer hang again. Can anyone help with a remedy? Messages works fine in Safe Mode.