Issue with exchange

Hi, I have a client who used to have windows 2000 and Microsoft outlook 2003 and he've got 1 personal email account and 1 production email. he've got lots of email but he could do some search email in "look for" inside outlook. Then I upgrade the pc with XP but keeping Outlook 2003 and now when he try to do a research, it's taking ages and a message appear on the outlook icone on the bottom saying "Microsoft exchange is retreiving ...." . Any ideas what that could be ????

Thanks for help me