We are seeing an issue that is occurring after an employee’s Operating System is upgraded to Windows 10.
After a computer is upgraded to Windows 10 and Office 2016 users are unable to use EXCEL .xlsx files in ArcGIS Desktop 10.3.1. Attempting to use an Excel file .xlsx file can cause ArcMap to crash.
During the upgrade Office 2016 is installed and all previous versions of Office removed. This removes the Office 2007 connectors that allowed 32 bit applications (like ArcGIS Desktop) to read.xlsx files. These are required if you have an .xlsx file you want to use in ArcGIS but do not have Excel 2007 installed. The 2007 Office System Driver can be downloaded from the Microsoft Download Center. If you have Microsoft Excel 2010 and higher or no version of Microsoft Excel installed, you STILL must install the 2007 driver before you can use .xls AND .xlsx files.
Install the Office 2007 data connectivity components from https://www.microsoft.com/en-us/download/details.aspx?id=23734.
Hope this helps someone!