You might try tightening the power steering pumps belt. Down by the pump the belt can be tightened by loosening the bolts, slightly, and then readjusting it to factory specs. Im not sure, but something like 1/4 to 3/4 inch deflection. Probably somewhere in-between.
If you get a fluid on the belt and pulleys, and the belt isnt perfectly tight, then what you describe can be exactly what occurs. Easy fix. Can be a knuckle buster depending on the location of the power steering pump though.
Try tightening your belt and then hit that baby with a mild pressure wash to get rid of any oil, gook, etc.