This is caused by incorrect MIME handling by Windows when 'DBF Viewer 2000' is installed. The 'DBF Viewer 2000' program associates the .DBF file extension with 'application/DBF Viewer 2000' instead of 'application/octet-stream'. Remove 'DBF Viewer 2000' from the affected system. If you are still experiencing the issue I can suggest this program DBF Repair Toolbox https://www.repairtoolbox.com/dbfrepair.html
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