Wel, I have been looking around the HP site and might mention some things.
According to the user's manual, the green button is for Teletext, with the Windows button being used to start Media Center. This may vary depending on your system. It also says some buttons work just like computer buttons, such as the power button, some work like hotkeys and some work differently from computer functions.
That being the case, I would suggest you update your software, especially in the area of HP Media Smart or Quickplay.
If that does not help, perhaps you could alter the hot keys to get you where you need to be. Maybe the hot keys were set up for a different directory or whatever and cannot find the Win 7 install. It appears to be in the...