why does my car only squeals when its first started up?

What is your question?

My car squeals on start-up, only for a few seconds, and will stop almost immeadietly if i put it into reverse or neutral. Will also only squeal if it hasnt already been started up within about 4 hours or so. sounds like a belt but i replaced both belts this year already. Any help you have for me is appreciated, thanks