in the past year, i discovered that my teenage son and his friends surf porn to an excessive amout on his computer. he swore to quit. needless to say, they didn't and i found out (i am very computer illiterate). first by cookies, then by jpeg files, then by history. each time i confronted my son, he wanted to know how i found out, and who told me how to do it. he knows that i know nothing about computers, so i told him i read up on it, but really i did it by haphazardly clicking around on my computer. after each confrontation, the method by which i discovered the porn no longer contained evidence (obviously, some sort of deletion). i am out of ways to find out what is going on. these boys, though young, are very smart. can anyone offer very detailed instructions on other ways to catch them. i know that the wool is being pulled over my eyes, but until my son is older (17-18yrs) i do not want him to view porn. so how can i find evidence of porn usage?