It depends on how you set your computer up. Do you allow User Switching? If so then someone might have been on it and locked their "window". Then you come in and log on and then you want to shut it down not knowing someone else just locked their session and may have work that they didn't save.
There is also remote desktop but typically for a workstation if you came along you would probably knock them off. On a server ou can actually have two remote desktop users and the console user (I'm talking about Windows Server). Do you allow remote desktop? It is usually a good thing if you want to log on to a computer hundreds or thousands of miles away and do some work without actually being there.
No, no remotes and the crossloop is only turned on when we might want our computer guy in Missouiri to fix a problem we caused and he is the only one with the password. I checked both of our pc's and they are the same. These are his & hers desktops. We rarerly have a reason to use the others. Mine is a Dell Deminsion E5200, his is an ATEN. We both use XP and have security updates in the middle of the night, every night. I access the internet through an Intac 3000 modem (he is close enough to plug into it) to a Cisco wireless.