First thing I would do is completly reinstall Office. This type of error is normally pointing to a dll that is improperly registered or not registered at all. I don't think the ISA server has anything to do with it. Are there other PCs on the same subnet as you? Are they working? George Taylor Systems Programmer Regional Health Inc. _____ From: Tee Darling [mailto:tee.darling77@xxxxxxxxx] Sent: Wednesday, January 31, 2007 12:53 PM To: isalist@xxxxxxxxxxxxx Cc: exchangelist@xxxxxxxxxxxxx Subject: [ExchangeList] Error "Interface not registered" My Outlook 2003 is behind ISA 2004 server. Every time I try to send an e-mail, I receive the error "Interface not registered". Has anyone seen this error before? If I reply to some of my old e-mails, I do not receive the error. It only happens when I typed in a new e-mail address. Now people don't seem to receive my e-mails when I reply to their old e-mails. Anyone seen the error before and how to resolve it? All searches on Microsoft, google and some other areas on the Internet have turned out to be negative. Thanks. Tee ***Note: The information contained in this message, including any attachments, may be privileged, confidential, and protected from disclosure. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the Sender immediately by a "reply to sender only" message and destroy all electronic or paper copies of the communication, including any attachments.