I received a desk top (acer) from the neighbor. Ever since then I keep noticing that when I try to delete something it says action cancelled by other user, or admin accessible only and Im the "only" registered admin that I know of. I delete something and the computer shuts itself off and the deleted program is back and blocked from me doing anything to it. Other things happen too its like someone has hacked a back door and i want to know if its so... i think he did something to it before he gave it to me. Theres too many things that happen when I try to clean it up.