A robot malfunctioned at the University of California San Francisco Medical Center, ignoring commands to go away.
Waldo shot past the pharmacy and barged uninvited into the examination room in the radiation oncology department, where -- according to an anonymous caller -- a doctor was examining a cancer patient.
According to the caller, Waldo wouldn't leave, and the startled doctor and patient felt obliged to flee the room.
Try this: the robot passed out medicines. It's noticed that a certain medicine in combination with radiation causes a higher percentage of people to eventually die of cancer. It finds out that this drug's been administered to the patient... and goes to stop the doctor.
Think about it; why do we assume that if the robot wasn't unknowingly doing this, it was doing it maliciously?