My POP3 server suddenly stopped responding. It's running, but when Outlook tries to receive mail from it the request just hangs. The service is partially communicating with the client though, because it sits there and tries. If I stop the service then Outlook immediately responds that the server is unavailable.
Also, the service won't start automatically. I have to start it by hand. The same is true of the Exchange Information Store and MTA stacks. I have to set them to manual, boot the server, then start the Info Store, then Stacks, then POP3. The last time I booted even the info store would not start manually until I stopped then restarted the System Attendant.