help

I am not a gamer, my son is. He got a Trojan on his computer (via a
friend using it) and I thought I had it fixed but now we're getting
weird Norton access stuff. The most common one is that a .rgn file is
trying to access the Internet. I thought .rgn files were associated
with colors and backgrounds in games (skins). If this is the case,
why would it be trying to access the Internet when he isn't playing or
even connected to the Internet? Please help. I cannot afford to buy
another computer.