connection to exchange server unavailable

Hello,
I have an outlook issue that I can seem to figure out. I have a computer
for some reason that I cannot get Outlook 2003 setup on to use my exchange
server. When I try to add the exchange server and username I get an error
message that says: The action could not be completed. The connection to the
exchange server is unavailable. Outlook must be online or connected to
complete this action. Everything else works fine on this computer. I can
ping my exchange server and everything. It isnt just 1 account either it is
any account I try to setup on the computer, signed on as different users.
Does anyone have any suggestions?
Thanks,
Ryan