Error - Cannot build recast graph

new project with A* pathfinding project PRO version, unity 4.1.3

when building recast graph I get lots of errors and unity eventually crawls to a stop:

DrawMesh requires material.SetPass before!
UnityEngine.Graphics:DrawMeshNow(Mesh, Matrix4x4)
RecastGraphEditor:OnSceneGUI(NavGraph) (at Assets/AstarPathfindingProject/Editor/GraphEditors/RecastGraphEditor.cs:161)
AstarPathEditor:OnSceneGUI() (at Assets/AstarPathfindingProject/Editor/AstarPathEditor.cs:1167)
UnityEditor.DockArea:OnGUI()

Trying to access pass 1, but material ‘Navmesh’ subshader (0) has only 1 valid passes.
UnityEngine.Material:SetPass(Int32)
RecastGraphEditor:OnSceneGUI(NavGraph) (at Assets/AstarPathfindingProject/Editor/GraphEditors/RecastGraphEditor.cs:162)
AstarPathEditor:OnSceneGUI() (at Assets/AstarPathfindingProject/Editor/AstarPathEditor.cs:1167)
UnityEditor.DockArea:OnGUI()

Trying to access pass 2, but material ‘Navmesh’ subshader (0) has only 1 valid passes.
UnityEngine.Material:SetPass(Int32)
RecastGraphEditor:OnSceneGUI(NavGraph) (at Assets/AstarPathfindingProject/Editor/GraphEditors/RecastGraphEditor.cs:163)
AstarPathEditor:OnSceneGUI() (at Assets/AstarPathfindingProject/Editor/AstarPathEditor.cs:1167)
UnityEditor.DockArea:OnGUI()

These errors just keep stacking up in the console and unity crashes soon after.

Please help. Only just purchased this today.

Ok, deleted the A* folder, re-imported and now it works.