Quote:

Do I need to have a map open? Do I need to have objects selected? I have tried it every which way to no avail.


Yes, you should have a map open with the data you want to convert to KML already in the data frame.


See text below image. (I am assuming you have ArcGIS 9 or higher, doesn't work on 8)



What worked for me was changing the path in Save to: (all the way at the bottom) to a path like C:\temp where I had a local folder. Then click the Export KML button. If you got the error before or during trying this I had to shutdown and restart ArcMap. It seems like only some people have this issue.

If it still doesn't work you can try Shape2KML v1.0

or wait and try Arc2Earth when it is released.