I'm running the latest Unity 4.3.0f4 and PM 1.7.5.f2. Starting a new, blank project with no add-ons, I can't access any of the PM windows. I've restarted Unity and there are no errors.
Actually 3 warnings I'm getting are:
Assets/PlayMaker/Editor/PlayMakerGUIInspector.cs(23,34): warning CS0618: `UnityEditor.EditorGUIUtility.LookLikeInspector()' is obsolete: `LookLikeControls and LookLikeInspector modes are deprecated.'
Assets/iTween/PlayMaker/Editor/iTweenMoveToActionEditor.cs(33,18): warning CS0618: `UnityEditor.Undo.SetSnapshotTarget(UnityEngine.Object, string)' is obsolete: `Use Undo.RecordObject instead'
Assets/Photon Unity Networking/PlayMaker/Editor/PlayMakerPhotonWizard.cs(103,34): warning CS0618: `UnityEditor.EditorGUIUtility.LookLikeControls(float)' is obsolete: `LookLikeControls and LookLikeInspector modes are deprecated. Use EditorGUIUtility.labelWidth and EditorGUIUtility.fieldWidth to control label and field widths.'