Collision jerks

Hi
we have built a wall with using a cuboid exported from maya(dts),the wall is placed irregular in shape (we used multiple cuboid to build the wall) this is not a concave mesh.
when the user moves along the wall he gets stuck or jumps in the same place inspite of going forward or
backward,this happens even at some distance before the collision wall too.

what could the problem be ?

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Thanks