[Got the Bug]

My V belt also screeches from time to time (usually when it's really hot out and the engine is up to temp). Check to see if the belt looks like it's glazed. If so, you may want to replace it again. Another option is to take some VERY fine sandpaper and rough up the V groove on the alternator. I've never tried it, but one recommendation was to take a light wire brush and rough up the V belt a little.

Last option is to change out the pulleys and go with a multi-rib belt. I've thought about this option, but it doesn't happen enough to really justify the conversion.