Hmm. Can we try this? How about creating a 3rd user from scratch. Also an Administrator level. Log in as this user. Does it have any problems with Office applications... will they work at all or prompt for the CD or are the installer errors being generated?
Also, it's worth a try I guess but I think it will prompt for the Office media CD but have you tried, in Add/Remove Programs, to repair the installation (under the user who is having the problems) and then also tried to see if there is an option to 'uninstall it' for the user or for the whole machine? This could potentially be dangerous because if there is no "are you sure?" failsafe it may put wheels in motion that cannot be taken back. /gulp