Hi - thanks so much for this website. It has helped my understanding so much. One thing I don't get is the downloads. There seems to be a download in my "downloads" folder every time my son plays. Do we need these and is this the same as the Minecraft folder you refer to?
I think what's happened is that you haven't finished the install properly to create a shortcut link that you can run it from (so Minecraft doesn't know that you already have it installed). Try moving one of those Minecraft.exe files to your desktop and running Minecraft from there... I'm pretty sure that should do the trick, if it doesn't then let me know!
Moved one of those files to the desktop and told my son to launch from there - just checked and there is nothing new in my download folder today! Thanks so much!