Hi, my husband has windows 10 also and the same thing started happening to him yesterday, so it is possible that it's related to windows 10. Today because I was fed up with having to keep closing down and re-opening the launcher to try and get the game to run I just left it after logging in. I was browsing the forums and when I went back to check it had logged me in and I could select the play button. I don't know whether that will work for you or not, or whether it's a one off thing I don't know, but I guess it's worth a try?