I reinstslled using just the browser, turned off AV and firewall, and it eventually did install and load.
If you're on Vista/Win7, and you have UAC on, it can't take a while for the installer to move on. Have you tried waiting a while to see if it eventually starts installing ? This
support article explains the UAC issues in detail.
If that's not the problem, make sure your AV and/or Firewall isn't blocking the install process.
Maybe try to download the game files again in case the first ones you downloaded are corrupt or something. You don't have to use the downloader, you can try to download them with your internet browser
As for an answer from support, they don't work weekends, so you'll probably ear from them this next week.