Last week a file ended up on my computer from my roomate's computer. Does anyone know how this would have happened? We have an unsecured wireless network. Something similar happened to a friend of mine last year, where files from his computer ended up on his roomate's, but I don't know how. I wanted to secure both computers so it won't happen again. Any information would be greatly appreciated so I can solve the problem, if possible, and put her mind at ease.