As far as I know,MDAC is part of the Windows 7 OS,so the only way to repair it would be
to remove and reinstall it again.
Starting with patch 5 of 7.30 GUI,the history will be taken from the jet database and the ACES one
will be used instead.
http://service.sap.com/sap/support/notes/1760341
Hopefully,this will improve things a bit.
Best Regards,
Jude