Outlook 2003 is available to one user account but not others

[Tom Barkas]

I've installed Office Professional 2003 on a computer with 4 User
accounts in Windows XP. I installed it from the Owner account and it
appears there, but clicking on Outlook anywhere in the other 3
accounts give a message saying "Cannot start Microsoft Office
Outlook". All other Office programmes work in all 4 User accounts.
I've installed the whole suite twice with no difference. Also
uninstalled Outlook on its own and installed it again - no difference.
Any ideas?