Outlook2002 error 48 opening dll

[Peter]

I have an Excel VBA macro that lists the contents of an Outlook folder
into a spreadsheet. Very handy and it works fine with Office 97 and
Outlook 2000. But on a PC running Outlook 2002, it comes up with
error 28 - error opening dll, and the line causing this error is
Set objOL = New Outlook.Application

This exact spreadsheet with VBA code works fine with Outlook 2000.

How can I tell which dll is causing the trouble?
Is there any other way round this?

TIA

Peter