Im having a little trouble with the program limewire.

Basically i seen a message left on my desk that my girlfriend had seen something on my limewire that she didnt like, the thing is though, i havnt used limewire in months, even years so have no idea how those type of files are there, as she said there are 63 dodgy videos.

I asked my friend if he knew anything about it as it was him who downloaded limewire on my pc to begin with and i know he has used my pc many times in the past. He admitted that he downloaded 1 porno before as a joke as he knows my family use it but after a couple of days deleted it after realsing i dont use it so never look at the files there.

My question is, is there any link to what he did that could of causd this, or if not is there any other way they could of got there?