Ain't that always the way? Do some one a solid by lending them your wheels, and she comes back lame... I'm not sure your level of experience with cars, but ...

1.) verify power steering reservoir has enough fluid. [easy]

2.) remove serpentine belt and spin/shake the pulleys you can by hand, looking for movement and listening for noise. [harder]

3.) Sounds like a bad idler pulley, but could be any belt driven component. Solution = replace. [hardest]

Good luck