Outlook 2003 connection issue

I have a machine on the network thats having issues connecting Outlook to the exchange server.

When Outlook first starts up it seems to take ages to startup and freezes. After 2-3 minutes an error appears:

“Unable to connect to the exchange server”

Once the user cancels out of the error it connects.

Any ideas on what could be causing this issue, or how I can go about resolving the problem?