Sis in laws PC. Win XP. Attempts to run disc clean up & it starts up, goes to the 3rd little box & then freezes & goes no further. Have tried it in safe mode, goes to 4th little box then no further. Have tried it with Firewall & Virus scanner disabled. Have defragmented - have checked for spyware & any viruses,also done scan disc & errors fixed. But nope- just won't clean up! Just stops. Anyone?!..