Occurrence

I am attempting to open a .xlsx file in MapInfo Pro 10 but receive the error -
"Microsoft Office Access Database Engine: External table is not in the expected format. Unable to open table"

Solution

This error occurs when the file is already opened in MapInfo Pro on another computer.

To workaround this issue, save the .xslx as a Excel 97-2003 .xls file, and recreate the MapInfo table.
This legacy format will allow you to open the Excel file in multiple MapInfo Professionals simultaneously.