Dream Problem
 

Im having trouble getting through the shaft in the 1st level (Dream) its like an invisible wall is there . If any1 knows the problem plz tell me :!:

The only way I was able to get through an invisible wall was to shut down the game, restart it, and try again. It did take a few times, but it finally worked. (Also, be sure to crouch when trying to go through low-ceiling shafts. I can't remember if the one you're talking about requires crouching or not, though.)