Same problem here and right out of the box too.
Problem: If I tilt the base 40 degrees or more (e.g., like when you are lying on your back with your legs bent in an A-frame position and you rest the MBP base on the top your upper legs at, say, 40 degrees from the horizontal-ground position) the display begins to move on its own to a closed position. And, from this position, once the display starts to move, momentum and gravity takes over and the display accelerates to an almost fully closed position (i.e., - that plus the loose hinge results in this problem).
Call me a slacker, but, while I realize the 17" display has significant mass, for the money I spent for my MBP, the ability to use it while comfortably laying back on a couch or bed is not too much to expect from the Apple design team.
Oddly, no matter what the starting angle of the display relative to a base in the horizontal position (e.g., 10 degrees, 20 degrees ... 70 degrees, 80 degrees, 90 degrees ... or 120 degrees), gravity does NOT cause the display to move on its own on my MBP - not even a little. Is this sounding familiar?
My questions: Is the hinge tension/resistance adjustable (i.e., can this problem be fixed)?
MBP 17" Mac OS X (10.4.9) 2.33 3GB 160GB 17"