Outlook problem

I have an issue that I can’t seem to find an answer for. I have a windows XP pro laptop with Office 2000 SR3. I connect to my work account thru our local LAN with a domain. Every time that I dbl click on Outlook, outlook forces me to put in my user name and password and domain in again. I am the only user with XP on our network, every one else has W2K Pro and nobody has to do this but me. Any suggestions would be greatly appreciated.