1999 Taurus, 3.0L DOHC V6. I started the car and first noticed the battery light was on like the alternator was not charging. Then I noticed that the power steering was not working so I assumed that I had lost the belt. I popped the hood and the engine is running just fine but the serpentine belt is not moving. I rev'd the engine and a loud hum sound followed and then the belt kicked on.... It drives just fine until I stop at a stop light and I get the constant humming sound whenever there is any load on the belt. I shut the car off and I can move the belt manually with little resistance. I can see the a/c compressor pulley moving, alternator pulley moving, etc. Any idea what is going on or how to fix?