Reality Factory

I'm working on a 2D- look-alike game. The levels are made only of sheet brushes and the whole level is wide only 3-4 texels maybe. So I have ground/floor which is a solid sheet brush and background sprites, which are empty sheet brushes. The problem is that the empty sheet brushes on the back cause collision problems. For example if I have a platform in the air which is a solid sheet brush and jump towards it from straight beneath the platform, my character goes through the platform while flying upwards and after the jump force stops it get's stuck in the platform, than if I jump again the character jumps and when and than it falls on the platform. I removed the background empty sheet brush and there was no such problem, the collision was OK... any ideas/help?

Thats pretty strange. Could be a bounding box problem? If the level is only a few texels deep it could act a little weird. Perhaps if the player spawned in with the bounding box already intersecting your background brushes you wouldn't be able to tell until you came to an edge, or something.

EDIT
Ah, wait. Old post. Probably fixed already?

Empty models have few collision problems.I have a jaw deep water model and the player can swim out of it also.
I hope these can be easily fixed.