Odd Bug with collisions?

Ive brought in my DTS shapes and collisions and it works fine, i cant run through it or shoot through it.
Problem is, when i built and imported a road, then proceed to jump on it. When i land, i start to slide across the entire mesh and most of the time i cant move in any direction while sliding other than the one that the inertia carries me. I cant find any instances of this in the forums or resources. Does anyone have any idea?

Thanks in advance