-e: We're assigning a physics material to a Terrain in Unity 4.3.3. If we save the scene and close Unity then re-open Unity the physics material is no longer assigned.

-repro:
--Create an New Project, no assets needed.
--Create a new GameObject -> Terrain in the scene.
--Create a new Physics Material in the Project.
--Click on the Terrain in the Hierarchy, click on the Terrain setting button in the Inspector.
--Assign the physics material to the Terrains Physics Material field.
--Save the scene in the project.
--Save the project too just to be sure.
--Close Unity.
--Open Unity to the same project.
--Click on the Terrain in the Hierarchy -> Terrain Settings.
--NOTICE the Physics Material field is blank.

The issue is fixed in Unity 4.3.7 Patch 1 version.