First and foremost, I have mmKeys installed correctly. My iTunes works almost perfect while minimized to the tray.
My problem is with the play/pause button on my Wireless Comfort Keyboard 5000. When iTunes does not have focus (like it's minimized, or if it isn't the application I'm active in, like right now while typing this) the play pause button toggles twice.
So, I'll push the pause button - and the song that is playing will pause, but a split second later will start up again. If the song is paused, and I push play, the song will immediately pause again. In order to get the key to work correctly, I must give iTunes focus, and then push the button.
Here's a video I created on youtube: http://www.youtube.com/watch?v=POh6Gbm5QZI
OS: Windows 7 x64
Edit: Apparently I have intellitype 8.0 instead of 7.1