Cannot forward mail

I have an end user with office 2003 running outlook from an Exchange 2000 server. Recently she stopped being able to forward email from an added mailbox within her outlook profile. Tried everything from profiles to reloading Office. Strange thing is now that I reloaded Office she no longer get the error “you do not have permission” it seems to forward or reply then we just get a system administrator alert. I added this mailbox to my own inbox and it works fine. Also tried her profile on another PC and receive the same result. Any ideas. Because I now have another person experiencing the same thing in Office 2000.