Mission planner keeps freezing

I am using Mission planner on my windows 7 pc.
When in the flight planner screen I setup a 4 way point flight but if I try to edit that flight by adding or editing a way point it freezes.
Any ideas please?

what version of MP?


I have tried it on my Windows XP computer at work and the same happens, it keeps freezing when editing Waypoints.

Someone else on the Facebook group Ardupilot is having the same issue.