Possible solutions:
Solution 1 – rebuild the icons cache:
- Open Windows Explorer
- Go to C:\Users\<username>\AppData\Local
- Change the properties of the folder so that you can see the hidden files
- Locate the file called IconCache.db and delete it
- Reboot the machine – the IconCache.db will be re-created and hopefully you will see the correct icons showing up for each of the Microsoft Office applications.
Solution 2 – repair the Microsoft Office installation:
- Go to start / Control Panel
- Under the “Programs” group click on “Uninstall a program”
- Find “Microsoft Office” on the list and click on it once to select it then click on the “Change” button on the menu bar on top
- On the dialog window that appears select the “Repair” option and click “Continue”
- This should repair any issues with Microsoft Office including a corrupt icons library.