pc stays on windows page?

hi iv got a big problem with my sisters pc, she wiped all her unwanter files, folders programes, etc , but now when you turn the pc on , it starts up then just stays on a windows page, which it usually does this then says loading then usually comes on but its not its just staying on the windows page, im trying to load a windows xp disc on to it for her so iv pressed delete when the pc starts up going in to the menue and changed the boot sequence so cd rom runs first, then when turning the pc on it says press any keys to boot from disc drive, then it says loading settings then says error code 7, she had this pc built by a friend and does not have any system recovery discs or anything with it, how can i fix this problem? please help and thankyou for reading