I have a 2000 C5, this week after driving for about 20 minutes i turned off teh car. Then after I restarted the car i basically lost my power steering, it "sticks" so to speak. not noticeable while driving, once stopped the power steering seems to stick. it makes a clicking sound while turing the steering wheel. fluid is at both marks whether cold or hot. Fluid is full. Any thoughts?

 

Could it be the serpentine (spelling) belt or a pully that is going bad?