Ran into the same problem 767driver. Like you, left well enough alone and did not install the program. The directions on fixing the problem is clearly marked on the web page.
Rather then messing with registering files per website directions, I have a sample file that below you need to save with the extention of .kml
I use Excel to import the data from Flight Aware (I copy the data from the FA flight log, and paste it into Excel). Be sure to put the cells in a general or text based format, not numbers or lead zeros will drop off.
I delete the unneeded colums.
I open Notepad, and paste in the following. You will have to add a comma between the coordinates as displayed below.
I snipped out the long string of GPS coordinates except for the first three entries for brevity sake.
3D Flight Path N9802Z
Save the above file in a .kml extension in Notepad in a notepad format.
If you got Google installed already, then all you need to do is double click your newly created file and Google will zoom into the flight track.
For the fly to feature to work, you may need to adjust Google to a selected altitude of your choice and fly the route.
Other then the tedious task of copying and pasting, and adding commas between the coordinates, this works great for me.
Takes me about 5 minutes from start to finish when I add a 2 hour flight into my Google Earth.
Hope this helps.