Removing local adminstrative rights causes issues

All employees at one location have administrative rights to their PCs. We are
removing Admin rights and giving all employees User access only. There have
not been any problems with the process for most, but a few of these employees
have been experiencing problems opening Outlook and a few other third party
applications after making these changes. The specific Outlook error received
is "Cannot start Microsoft Office Outlook".

Users are running WinXP Pro SP3, on Active Directory Win2003 Svr Std SP2 and
Office 2003 with the latest service packs.

TIA...

e.