Error 1706 - Office 2000 on XP Pro

[DaveC]

Installed Office 2000 Small Business Ed. on XP Pro under
Admin account and updated via SR-1 to SP-3 pluis security
updates with Office Update.
Log on as the normal Restricted (Power) User and I keep
getting "Error 1706. No valid source could be found for
product Microsoft Office 2000 SR-1 Small Business. The
Windows installer cannot continue." when starting Word or
Excel.
Why does it quote SR-1 when SP-3 is installed?
Why do I get this error message? and how can I get round
this?
Hoping in anticipation...
Dave