I figured out why I was seeing only "green" in the map perspective of Google Earth. I went to their help troubleshooting and saw something similar for Macs needing to enable accepting "cookies" from this Google Earth site. I had upgraded to IE 7 in the past month and suppose that it reset my security settings and sites that I accept cookies from. So, I added that site in IE options > security and also in my PC's security software to accept cookies from that site. It now works for me. Thanks for the suggestions.