You Can Fix It

First you must Unhide the Windows 7 System and Protected Operating System files.

In your Windows Explorer, navigate to C:\Windows\Globalization\MCT
Open a MCT-AU (Australia), CA (Canada), GB (United Kingdom), US (United States), and ZA (South Africa) folder for the regional theme that you want.

Double click to select the .theme file to load it.
You can add multiple themese by reapting this steps for each folder.

Once you select a .theme file, Windows 7 will load it so that you will be able to change or select this theme again from within the My Themes area in the Personalization window.

Remember to return and Hide the Windows 7 System and Protected Operating System files

You can now add the theme to the Aero Themes area instead in the Personalization window