I too am seeing this same behavior with ReadyAPI. It just started this week.
I'm using Ready!API 1.5.0-m-snapshot.
Additionally, when I do use File--> Exit Without Saving, the next time I launch reaadypi, the projects I had loaded are all removed. I have to re-import the projects.
I've been using this version since the snapshot was released on this same OS (windows 10, Version 1511, os build 10586.71, 64 bit)), and this behavior just started this week (Wednesday 2/3/16), or there abouts.
I have also tried uninstalling and re-installing, but that has had no effect. I did install Java recently, though, this behavior didn't happen immediately following that. I've since uninstalled java, but that also has had no effect.