Forwarding issue in Outlook 2003

I have a user that has an issue every time he forwards an email in his outlook 2003 he gets this message: Contact is not in contact list. The contact is in his history list, but not in his contact list. Why would this error message be coming up? Also, the other day, he (same user) could not put a contact in his contacts list without going through a modem setup screen. Connected???? Thank you