A list of multiple things I could do would help. I share a computer with some assholes in my computer class and they keep changing the background to something inappropriate. I locked it before with the local group policy editor and that kept it locked for like three days, and then they figured something out, and its no longer locked through the group policy editor. Are there other programs that lock it? Is there a way to set it so you need a password to change it? (also im not going to the teacher about it because then i'd be in trouble too)

thanks