This issue started a couple of days ago on my 10.5 Pro. Several apps, like the AppStore, Amazon, Xfinity Stream display their splash screens when startin only for them to stay on the splash for a period much greater than normal (> 30 secs), and then they crash back to the main screen. Restarts, reinstalling, resetting network settings, etc fixes this. I just have to keep trying until I get in. Has anyone even heard of anything like this before?