There's a guy
here who set this machine to have a special prompt a lot like yours (about half way down the page).
You should be able to see if anyone else is logged into your machine by typing
who. Then if you don't find another user logged on, try
Code:
find . -type f -exec grep -l "torvalds" {} \; -print
assuming of course that your machine name isn't actually "torvalds". Otherwise, change that string to something else like "trol in this shell" and you should be able to find the file where they changed the default login prompt. I assume it's probably /etc/issue, .bashrc, or .bash_profile...
Also, you should follow
this page to enable the root account and set a new password for it. then also change your own password.