1. In Add/Remove programs, locate your Office application and select it.

2. Click on the 'Change' button

3. Select 'Add or Remove features' and click 'next'

4. Select 'Choose advanced customization of applications' and click 'next'

5. In the tree view, expand 'Microsoft Office Excel' and make sure the .NET Programmability Support option is set to 'run from my computer'.

6. Click 'update'