Hi Medic,
You may want to check to see if you've installed the optional feature for MS Office Document Imaging through the Office 2007 choice
in Add/Remove Programs in the Windows control panel.
Other than one 3rd party viewer, that optional Office feature is the only basic one that handles the .mdi file format.
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Whi can't I open a file saved in office 2003 (MDI) in office 2007?>>
--
Bob Buckland ?

MS Office System Products MVP
*Courtesy is not expensive and can pay big dividends*