Rpc over Https problem

Hi People:

I´m using windows vista beta 2 and outlook 2007 beta. For access to my exchange´s mailbox i do using rpc over https. Well the problem is i configure my PC in the office then the IE (or something) assign the internal ip to the certificate and when i try to access throw internet the IE i see this: This organization's certificate has been revoked. Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server. Any suggestion?

King regards.