When you are attempting to view or edit and Excel workbook in the browser you may the following error:
1. Go to Central Administration and find Manage service applications.
2. Click on Excel services Application.
3. Then click on Trusted file locations
4. You can set url field to https:// (or) specific location
5. Fill in the boxes and also ticked the trust check box
Simple Isn't? :)
Happy Share Pointing Folks :-)