First off, I wasn't sure which forum I should post this in, so I'd like to apoligize before I get 500 people yelling at me.

I am making my own movement function from scratch, and what it does is i make a couple vector that keeps track of about unit below the players feet. I trace from one vector to another, and if the trace makes it all the way across (then there is obviously no object there to block it) then i move the player down a little bit. So this way, the player falls down if nothing is below him.

Now here's the problem:
When I use a .mdl for my ground, it doesn't always register right. Like I can make just a normal block and walk around on it and he'll fall down when he's still got a ways to go before the edge. It's like the engine does'nt accurately read where the block begins and ends or something.