"Can't run it - blocked by XProtect"
Is System Integrity Protection on?
Open terminal and type
csrutil status
then hit return
It will tell you.
If SIP is on, here's how to turn it off:
Boot to the recovery partition or to internet recovery
When you get there, open terminal and enter:
csrutil disable
Then, reboot.
Try opening the app now.
If it STILL won't open, you can disable Gatekeeper by doing this:
Open terminal and type
sudo spctl --master-disable
Hit return
You'll now be asked for your password.
Enter it (IMPORTANT: you WILL NOT SEE your password as you enter it)
Hit return.
Now try opening the app.
Any better?
NOTE:
In the above terminal commands, you can "copy and paste" them into terminal.
Be aware of the single space characters between the phrases.
NOTE2:
If you're not comfortable using terminal, there is an OLD utility called "Mountain Tweaks" that still runs and can disable Gatekeeper for you.
Get it here:
Mountain Tweaks is a tweaking tool to deal with the annoying changes in OS X 10.8 Mountain Lion. Mountain Tweaks focuses on a user friendly user-interface, even more tweaks and the ability to do simpl...
mac.majorgeeks.com