iTunes slows PC after closing

I use iTunes to sort and play my MP3's. Every time I close iTunes my computer slows down to a snails pace for about 2 minutes. I have monitored CPU and memory usage but nothing odd happens during those 2 minutes, and no major hard drive activity happens either. I have 2GB's of memory (DDR2) and a 3.2GHZ P4 CPU. I have 3 HDD's (60GB, 120GB, 200GB - all PATA). The MP3's are on the secondary master IDE (200GB). Can't figure out why it does it. Running XP Pro.