MSWORD 2007 - Mailmerge file association

Hi Experts

A client with MSoffice 2007

She has been creating mail merges by creating a source document then adding manually a list of addresses and then saving them a file for later re-use simply using the wizards/icons from within the word program.

For reasons, unknown she then had a problem opening one of the saved documents and its associated list.

The lists are saved in her data sources folder under my documents and are in the format filename.mdb

In an attempt to "fix" the problem she manually changed the file association for .mdb files to Powerpoint.

I suspect that the association needs to point to MSACCESS but ( and this is the basis of my query) her version of Office 2007 does not ( and never has) included Access ?

What is the correct file association/data source settings we need to correct this?
(MSACCESS.exe is not present on the pc).

I have tried an Office Repair - Via add/remove programs - no joy.
System restore is an option but the latest restore point on the system is dated Oct 2011
So suspect that may create more problems than it solves ?

Any help much appreciated