Thanks for the replies, you were both spot on. I'll just have to find out what my son has been doing with the computer to get this virus.
most of the easter eggs are hidden in some shareware files, freeware files, internet porn diallers, spyware, warez cracks/serial patches etc... (warez being illegal).
so to be honest dont give ya son too much of a hard time, he was either unlucky to receive it from a legitimate program or hes been a naughty boy on warez and/or porn sites, but i doubt he'll be honest if hes been found out