Outlook 2000 not respoding to exchange

I set up a Windows XP Pro on my network and installed and configured my outlook client, worked great. It contiuned to work for 5 days and then it stops. So I delteted my outlook profile and went to create it again, set up exchange server client and when I press check name it goes none responsive. So I uninstalled Outlook reinstalled updated to SR-2 downloaded all the XP critical, recomended and driver updates so the machine was totally updated and still the problem is there.

Any thoughts:)