diff --git a/examples/OpenGLWindow/GLInstancingRenderer.cpp b/examples/OpenGLWindow/GLInstancingRenderer.cpp
index 26d765536..1a66c32df 100644
--- a/examples/OpenGLWindow/GLInstancingRenderer.cpp
+++ b/examples/OpenGLWindow/GLInstancingRenderer.cpp
@@ -1618,7 +1618,7 @@ void GLInstancingRenderer::renderScene()
 	{
 
 		renderSceneInternal(B3_CREATE_SHADOWMAP_RENDERMODE);
-		glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
+		
 
 		if (m_planeReflectionShapeIndex>=0)
 		{
diff --git a/examples/OpenGLWindow/Win32OpenGLWindow.cpp b/examples/OpenGLWindow/Win32OpenGLWindow.cpp
index 28eab35cb..aa71750ad 100644
--- a/examples/OpenGLWindow/Win32OpenGLWindow.cpp
+++ b/examples/OpenGLWindow/Win32OpenGLWindow.cpp
@@ -119,9 +119,9 @@ void	Win32OpenGLWindow::closeWindow()
 void	Win32OpenGLWindow::startRendering()
 {
 		pumpMessage();
-		//don't clear all 3 buffers because some AMD drivers are buggy
-		//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
-		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+		
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
+		
 		
 
 		//glCullFace(GL_BACK);
diff --git a/examples/pybullet/pybullet.c b/examples/pybullet/pybullet.c
index 4e0785021..1fae95a6d 100644
--- a/examples/pybullet/pybullet.c
+++ b/examples/pybullet/pybullet.c
@@ -937,6 +937,12 @@ static PyObject* pybullet_changeDynamicsInfo(PyObject* self, PyObject* args, PyO
 		return NULL;
 	}
 	
+	if ((contactStiffness>=0 && contactDamping <0)||(contactStiffness<0 && contactDamping >=0))
+	{
+		PyErr_SetString(SpamError, "Both contactStiffness and contactDamping needs to be set together.");
+		return NULL;
+	}
+
 	{
 		b3SharedMemoryCommandHandle command = b3InitChangeDynamicsInfo(sm);
 		b3SharedMemoryStatusHandle statusHandle;