My regedit is blocked!!!!

when i start up my computer there is no icons, start, or whatever... other people have had this problem and i tried one solution that involves alt crtl del and getting task manager up, then to write regedit into the new task thingy but its blocked by the administer ... and i am the administer .... grrr ... its windows vista basic toshiba sattelite something or other ... PLEASE HELP