I fully understand your concerns. Sometimes I think there are only a couple of different cleaners, because they all seem to have been written by the same guy! - and I get nervous, because what if that is the wrong guy?! haha..., yeah, but... I have the PRO set in mention, but I have never used them, because a part of me don't dare! In the days of Win2000 I made my computer unreachable, by using a poor registry cleaner. That lesson keeps popping up in my spine every time I wonder how to help my computer run faster; "how do KNOW if my cleaner is both useful & harmless?"