A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
I am getting this problem and it isn't about the file association as the double click does indeed open Excel the problem is that Excel then does nothing. You can open files form inside Excel but not in any other fashion.
This is substandard, frustrating and there appears to be no help from Microsoft on the issue. All knowledge base articles are out of date or do not answer the specific question.
I really wish I hadn't bothered upgrading from 2007.