There appears to be a conflict between the controls that steer the ship and those that land it.
(Just a guess)
The result is I can fly around blasting all sort of ships but not progress in the game. However, hovering over the landing platforms while the small white arrow appears pointing down, there is no keyboard combination that cause the ship to land.
I've read lots of comments on this board and the difficulty of many of the obstacles or puzzles seems to be due to design of the user interface not the game itself. I'm not sure if that is the issue here or if this is a bug.
Windows XP 64-bit fully patched
Intel Core 2 Duo P 7450