I've had Office 2010 installed for a long time.
About a week ago I installed Office 2016.
Today I uninstalled Office 2010.
Since then I cannot open any Excel files by clicking on files with extension .xlsx
I get an error message similar to this:
D:\Dropbox\Dropbox\_Mincad\Admin\MailChimp\lmports - Adhoc or CPEE lists\MailChimp
Import Template - Ad Hoc - To Be Added.xlsx
This action is only valid for products that are currently installed.
The File association for .xlsx files points to Excel 2016: