Outlook Express

Ever since I started running XP Pro edition a few weeks ago my Outlooks takes forever to start up (2 minutes). I read somewhere that I have to delete the registry keys and when I do this it starts up great. But then after I reboot the keys go back to how they were and it takes 2 minutes to load again. I don't know if anyone else has had this problem but if you have any idea how to fix it please help me out.