My car just had the serpentine belt changed 2.

Have you looked under the hood to be sure the belt is there where it's supposed to be? Almost sounds like you lost the belt from the sounds of things.

On a side note, I tried a goodyear cross cut serpentine belt that was highly recommended on a Suburban and kept throwing the belt, it wasn't until I went back to the conventional belt with no cross hatch design and only grooves aligned with the belt that this problem simmered down and I quit throwing belts. At temps like that, could your coolant not have been low enough and that created the issue (ie. Freeze up)?