This issue began last evening when I was unexpectedly logged out of iMessage and FaceTime on my MBP. Attempting to login to iMessage yielded an error about this not being a registered device for this login (paraphrasing). For FaceTime, attempting to login, the login screen would just refresh. After a few hours and a restart I was able to log in to iMessage and all has worked fine with iMessage since then. But as far as FaceTime is concerned, I have not been able to login. Attempting to login with another account is performing the same, the screen just refreshes but never actually logs in. Has anyone else experienced this issue?