You don't have a license required to use this ActiveX control

Hi all, I'm using a Microsoft access database of contacts and one function I
use which works fine when I use it under Office 2000, however when I try
this using Office 2003 I get the following error message. "You don't have a
license required to use this ActiveX control" and the macro halts.

Can you advise what this is all about and what the easiest way to correct
this problem is, as I would like to use the database under Office 2003.

Any advise and solution greatly appreciated