Unable to open files directly from explorer in Microsoft Excel

If you have troubles opening a spreadsheet file in Excel when you double click on the file.

To fix this common issue, do the following.

1. Open Microsoft Excel
2. Go to Tools-->Options
3. Go to the General Tab and UNTICK “IGNORE OTHER APPLICATIONS”
4. Select OK.
5. You should now be able to open Excel files again

In excel 2007 this option is found under menu, Excel options

Check off Ignore Applications that use dynamic data exchange (DDE)