Rigid body collides with edges

[Bellbird Creative]

I've got a Rigid Body cube with a simple 6DOP Simplified Collision and a Physics Material with 0.02 friction. It slides along just fine but whenever it meets a join in the BSP or an edge in a mesh it collides with it and either bumps over it or stops completely, even though the surface is completely flat.

Has anyone else experienced this or knows how to work around it?

[Bellbird Creative]

Bump... No ideas?

[Bellbird Creative]

Looks like this is happening to a few people: http://forums.epicgames.com/threads/...kipping-occurs!