my wifes 01 burb does the same thing, it can get really annoying when she keeps saying the "car" (ugh!) keeps making that squealing noise...I have sprayed it with a lil belt dressing and that seems to help for a while....then she starts squealing again.....lol
try picking up a can of belt dressing and spray the serpentine belt. unless you know what your doing under the hood spray the belt with the engine off. If you do it with the engine running you risk injury.