internal smtp mailbox unable to forward messages to exchange mailboxes

I have a user who has multiple accounts open in her outlook. All of which are SMTP. for some reason once a message from an outside server is downloaded to the inbox, she cannot forward any message from this inbox ( which is not an exchange account)to internal exchange recipients. But I can open this mailbox on other users outlook accounts and there is no problem forwarding. Platform: win XP on exchange 2003 running outlook 2003. I have checked and doubled checked her profile settings both in the AD and local.