I have seen this several times.
Macros – Check the autoload/startup for Microsoft Excel.
(Open Excel – Tools Menu – look at Add-ins & Macros)
Probably a macro setup as default under a previous version of Excel. New versions of Excel ‘protect’ you from macros that would run automatically. You double click the spreadsheet – Excel throws an exception – the error message and file open aborts while you deal with the message. If Excel is already open the file will open an does not error becausee the the macro/addin has already been dealt with when you started Excel. The give away is the error on exit.