I just so happened to have clicked into the Windows Task Manager and there, under the Users tab, is a second user with ID 2 ... Mcx1. Under the Session column it says EH-TCP#0. Who on earth is this second user on my computer??

A hacker! You've been owned. :cheesy:

Actually, it's some sort of default user, also present in Windows XP... I think it's got something to do with mapping network drives, but I can't be completely sure. MCX1 is a some sort of network device, so I believe Windows uses it somehow for that purpose.

It is a Media Center Extender account. (Media Center Extender example: the xbox 360) It creates its own account so it can interface with your computer. Media Center Extender accounts will always be named MCX#.

Gotcha ... I thought it was something like that because I went to restart my computer last night and it gave me this message about having someone else connected to my system. I powered down my XBox360 and it let me reboot message-free ... BUT with the Xbox360 turned off, it still had that second user listed.