Jenny,

Are you on an Exchange 2003 server using Outlook 2003?

If so Microsoft's support site has an article on this. The error has to do with the Offline Address Book.

Error message when a user performs the Send/Receive operation in Outlook:"Unknown error 0x8004011B"

If you are on Exchange 2007 the error is probably occuring because you do not have an Autodiscover Cname set up for your domain's DNS records.

Hope this points you in the right direction!

Masta7Mail
seamlessly connected via hosted Exchange with http://www.themessagecenter.com