When you open a kmz file you may see a large red X instead of a map or photo.
The kmz file you downloaded includes the map image, a jpg file, and the kml file.
Right click on the file and Save As into a file on your hard disk where you can find the kmz file.
The kmz file can be Unzipped with WinZip or other such software and extracted into a folder on your disk. Find the file in Windows Explorer or WinZip and do this now.
When you do this you will see doc.kml and /files with the jpg image in it. Extract them into a file you can find easily. /Temp or Desktop are common locations.
Open that doc.kml file with Google Earth and the image map overlay should work for you.
If not, then right click on that kml file (in your Places section of Google Earth) select Properties, and then Browse to the jpg file and select it. Close Properties and you should see the map.
