Installation of beta 5 is freezing when I paste serial key

I’m trying to install the latest beta and each time I try to paste my serial key, the dialog just freezes and I have to force quit.

running an iMac 2012 with yosemite and all the latest updates

download beta 14? in the release notes it says they fixed that.

http://unity3d.com/unity/beta/5.0/release-notes

  • Editor: Fixed crash when pasting in License window on OS X