I don't get any error when I exit using CF's button. Sometimes with GENexus if you close it through CF, Google Earth and CF will lockup. If you then End Task on Google Earth, CF will work again. I have not figured out how to fix this problem yet, but I think it is related to the way I embed the Google Earth window. I do not have any problems with iGNexus.
I'm not sure I fully get your solution. Basically you just removed the shutdown= commands and made a new button that does those same commands right? What do you mean about the OSK title fragment?
Anyway, I would also like to point out that I never close any app in the car. You should just use the Main Menu button in the upper left to switch away from it. That way it doesn't have to re-load when you switch back. Why do you need to close it for anything other than testing / skin-creation?