I have a Mac Mini with file sharing and screen sharing enabled. I've always been able to connect to the shared folders on the Mac Mini from my MBP until this morning. I still see the Mac Mini listed in my MBP's finder and screen sharing still works. But when I tried to connect to the Mac Mini's shared folders, it just says "Connecting" for a long time and then fails. By the way last night I've updated the Security Update 2013-003 on the MBP.