[zagrot]

that sounds like a pulley alignment problem or belt tension. by the way, never spray a belt or tire with WD40 since it weakens rubber. insted get a spray bottle and spray the belt with water while it is running, if the squeel gets loud and then quiets after a while the belt tension is low, if the squeel gets quite and then loud later the pulleys are misaligned -- one is offset from the others; lateraly misaligned i believe. it could also be a bad bearing, but the water test will not cause a change in the noise if that is the case. and as always if the belt is cracked, frayed, oil saturated, or badly glazed it should be replaced.