delayed mail after xp sp2 install

I have 2 systems with xp pro. one has office 2000 sbe, the other office xp sbe. both office install were upgraded to the current service pack before sp2 install. Outlook on both systems is used to access Exchange server 2000.
After installing xp sp2 on both systems, new mail will only be received after clicking on the new mail button in the toolbar.
I have tried uninstalling sp2 then office and putting sp2 on 1st then office, no luck. The only way I have fixed the one system with Office XP is to format, install xp pro then sp2 then Office XP.
I have some systems with Office 97 and Outlook 2000 on them, all have been upgraded to sp2 and do not have any problems receiving mail.
Anybody got an idea what the problem is?
Thanks,
Ed