450mb on my 13" MBP....
.....And, it broke my backlit keyboard.
Seriosuly. Whenever I try to turn on the backlight, I just get the "no can do" rather than a brightness level.![]()
This might be a stupid question, but are you in a bright room. I have never been able to turn on the keyboard backlight unless I was in a sufficiently dim room. If the light is on in my office, I encounter the same thing you describe, but that's normal.