Ps2 backup

hi everyone. i just started backing up ps2 games. i have run into 3 different games that when i went to play them, they had waves on the screen. I dont know exactly how to describe it exactly, but almost like the ppv channels used to look when they were blocked out. but its like one consistent thing that goes from top to bottom and then starts again, the whole screen, so like the game is consistently moving down the screen. but i have had other ones that worked fine. so my question is why is it doing that? is it in the copy process or am i doing something wrong burning it?