When opening Excel if you are getting a Protected View error and it is saying the file is corrupted and unrecoverable.
1. Open a new Excel workbook
2. Click File -> Options
3. Click Trust Center -> Trust Center Settings
4. Click Macro Settings and make sure the following settings are set
5. Click on Protected View and make sure none of the options are selected
6. Click on External Content and make sure these settings are set
7. Click OK -> OK to save the settings
8. Close and re-open Excel