Getting the same 1603 when installing google earth pro as well. Unfortunately I'm one of the suckers where it's not an issue with just a missing shortcut. Nothing in the Google folder so I'm not trying to reinstall.
Tony’s Answer: This error can startle even the most experienced PC users because they happen so suddenly. You might be working on a document or just talking to someone online, and then suddenly the Error 1603 Google Earth Pro appears.
I am trying to download the upgrade of Google Earth to google earth pro. Attempts on my desk top, running Vista, resulted I'm me being told that I cannot, because of error 1603. Trying on my I-pad 2 produced a message the Safari cannot handle the job!
I had the same problem when I tried to install PRO after the googleearth installation. During installation of google Earth Pro "1603" error occured. I closed my google earth session, started setup again and again - always 1603 error