Can't Install Avast Pro

I just downloaded the installation file for Avast Pro. When I try to install it, it tells me that “You are trying to use an old version of avast setup. Instead of using the packages in this file, the installer will download and use the latest setup from the internet.” I click okay, then it tells me that “Setup GUI was not initialized successfully.” After that it does nothing when I try to use the install program, just shows the avast logo installing for a few seconds. What’s going on? Any help will be greatly appreciated, thanks!

  1. Download avast! Pro Antivirus: http://files.avast.com/iavs5x/avast_pro_antivirus_setup.exe
  2. Follow instructions: http://www.avast.com/uninstall-utility (Run this tool for all prior installed avast! versions…!!)
  3. Reinstall avast! with the downloaded installer from point 1.
  4. Reboot.