Error Message: File Corrupt

First, make sure you're using the required version of Excel.  This issue seems to be related to Excel 2010.

Then, try the following steps:

1. Open Excel
2. Click on File > Options.
3. Select Trust Center > Trust center settings.
4. Select Protected view.
5. Uncheck all the options under Protected View > OK.
6. Restart Excel and try to open Excel documents.