You might want to question him what he did on his computer and what his password was (you know, how short and easy the code is).
Watch yourselves on MMO forums. People tend to make threads that include infected links that'll result you handing your own MMO ass over for nothing. Any fishy links must be avoided. And stop clicking one those x-rated links too, that'll be extremely useful.
You must consider some very important steps dealing with account security:
1 - Avoid using the same username on multiple sites.
2 - Avoid using the same password on multiple sites.
3 - Use passwords that are quite long and involve numbers and other things (!, @, #, $, % etc)(if possible).
4 - An add to number 3: If you got trouble remembering your password, just stick a sticky somewhere in your room with some of your listed usernames and passwords. Better safe than sorry.
5 - Like I mentioned: Avoid them fishy links!
6 - In MMO's: TRUST NO ONE. Seriously, they're all there to get you, and I'm not being paranoid about it.