I've been paranoid recently about a thing that has been happening for more than two weeks now. Every time I felt my iMac slower than normally is and the beach ball from hell start appearing more than usual I check my user name in my menu bar and for some reason the Guest Account has a check mark as if someone was using it before me. I was in the believe that because I normally use 'Screens' in my iPhone to access my iMac for some reason the guest account activate it self as a bug on the 'Screens' app or something else. I'm the only one who use my iMac. No other person have access to it so that's why I was like: "What is going on with this 'Guest Account' being active every now and then?" Ok, Well... last night I was working late on a audio-editing job on other computer in the same office at 2am in the morning when suddenly everything start happening in front of my eyes! my Mac wake up and login by itself as a guest account open up safari and went to a Whoiswhatever.com site and search for my IP address info! What? or Who? or Since When? OMG now I'm scare and honestly I don't know what to do now, it's obvious that someone is accesing my iMac but who? how can I stop this? Is there a way to block guest access account? Please Help. My immediate solution is turning off my iMac at night but I need it in standby always for my job needs. Please any help will be apreciate it.