I am the System Administrator of my computer. I have managed to limit most of what my nephew can do via general Windows functions. However, I need to prevent him from changing his Firefox Options (listed under the Tools menu). He has already changed items that leave my computer vulnerable and although I've explained to him that he should not change anything in the Options area, he continues to do it. If there is not a way for me to prevent him from changing anything in Options, then I have no alternative than to prevent him from using the computer at all. I hope it doesn't come to that.