I hate jumping problems. I can figure a maze; I can solve timed problems; however, if a game requires that I hit a switch, run really fast, and then maneuver some jumps all before the door/gate/bridge closes again, I'm screwed.
Hence my stuckness on level 18 in Portal. I know what I have to do. I have to hit the switch which makes the wall pop out and tilt . Then I have to get back on the ledge, make a portal on the titled piece, jump off the side, and make another portal which will then catapult me with my existing momentum over the watery void to where the weighted companion cube sits.
And I can't do it.
I come out at the wrong angle. I can't get of the steps fast enough. I don't jump off the ledge right, and fall into the water. I just plain run out of time.