Nope, not a virus. I checked a while back when I was having other problems (which occurred long after this problem began). Besides, this whole Lemmings file stuff occurred before this computer had Internet.
EDIT: I probably will tonight, because I just remembered, when I did research on DrWatson Postmortem Debugger, I read at several places that it can mask some kind of, if I'm not mistaken, Trojan virus known as "Acebot."
I bet if I was using a different OS, this wouldn't be a problem! Of course, Linux might be a bit difficult to use, from what I hear, and my computer can't handle Mas OS X.