diff --git a/composite.cpp b/composite.cpp
index c0878dfea2..c7d5c3a271 100644
--- a/composite.cpp
+++ b/composite.cpp
@@ -84,7 +84,7 @@ void Workspace::setupCompositing()
         }
     else if( !CompositingPrefs::compositingPossible() )
         {
-        kDebug( 1212 ) << "Compositing isn't possible";
+        kWarning( 1212 ) << "Compositing is not possible";
         return;
         }
     if( scene != NULL )
@@ -147,7 +147,7 @@ void Workspace::setupCompositing()
         }
     if( scene == NULL || scene->initFailed())
         {
-        kDebug( 1212 ) << "Failed to create Scene object. Compositing disabled" << endl;
+        kError( 1212 ) << "Failed to initialize compositing, compositing disabled" << endl;
         delete scene;
         scene = NULL;
         delete cm_selection;
diff --git a/lib/kwinglutils.cpp b/lib/kwinglutils.cpp
index b6fc33e75e..afc4a9d491 100644
--- a/lib/kwinglutils.cpp
+++ b/lib/kwinglutils.cpp
@@ -99,11 +99,15 @@ bool hasGLExtension(const QString& extension)
     return glExtensions.contains(extension) || glxExtensions.contains(extension);
     }
 
-void checkGLError( const char* txt )
+bool checkGLError( const char* txt )
     {
     GLenum err = glGetError();
     if( err != GL_NO_ERROR )
+        {
         kWarning() << "GL error (" << txt << "): 0x" << QString::number( err, 16 ) ;
+        return true;
+        }
+    return false;
     }
 
 int nearestPowerOfTwo( int x )
diff --git a/lib/kwinglutils.h b/lib/kwinglutils.h
index e754b2261a..1c5e1fe0ea 100644
--- a/lib/kwinglutils.h
+++ b/lib/kwinglutils.h
@@ -61,7 +61,7 @@ bool KWIN_EXPORT hasGLXVersion(int major, int minor, int release = 0);
 bool KWIN_EXPORT hasGLExtension(const QString& extension);
 
 // detect OpenGL error (add to various places in code to pinpoint the place)
-void KWIN_EXPORT checkGLError( const char* txt );
+bool KWIN_EXPORT checkGLError( const char* txt );
 
 inline bool KWIN_EXPORT isPowerOfTwo( int x ) { return (( x & ( x - 1 )) == 0 ); }
 /**
diff --git a/scene_opengl.cpp b/scene_opengl.cpp
index ff0b0b1e7e..3722bd53c4 100644
--- a/scene_opengl.cpp
+++ b/scene_opengl.cpp
@@ -125,7 +125,7 @@ SceneOpenGL::SceneOpenGL( Workspace* ws )
             !glXGetVisualFromFBConfig || !glXCreatePixmap || !glXDestroyPixmap ||
             !glXCreateWindow || !glXDestroyWindow )
         {
-        kDebug( 1212 ) << "GLX_SGIX_fbconfig or required GLX functions missing";
+        kWarning( 1212 ) << "GLX_SGIX_fbconfig or required GLX functions missing";
         return; // error
         }
     if( !selectMode())
@@ -162,7 +162,11 @@ SceneOpenGL::SceneOpenGL( Workspace* ws )
     glOrtho( 0, displayWidth(), displayHeight(), 0, 0, 65535 );
     glMatrixMode( GL_MODELVIEW );
     glLoadIdentity();
-    checkGLError( "Init" );
+    if( checkGLError( "Init" ))
+        {
+        kWarning( 1212 ) << "OpenGL compositing setup failed";
+        return; // error
+        }
     kDebug( 1212 ) << "DB:" << db << ", TFP:" << tfp_mode << ", SHM:" << shm_mode
         << ", Direct:" << bool( glXIsDirect( display(), ctxbuffer )) << endl;
     init_ok = true;
@@ -363,7 +367,7 @@ bool SceneOpenGL::initBuffer()
         }
     else
         {
-        kDebug( 1212 ) << "Couldn't create output buffer (failed to create overlay window?) !";
+        kWarning( 1212 ) << "Couldn't create output buffer (failed to create overlay window?) !";
         return false; // error
         }
     return true;
@@ -445,7 +449,7 @@ bool SceneOpenGL::initBufferConfigs()
         XFree( fbconfigs );
     if( fbcbuffer_db == NULL && fbcbuffer_nondb == NULL )
         {
-        kDebug( 1212 ) << "Couldn't find framebuffer configuration for buffer!";
+        kWarning( 1212 ) << "Couldn't find framebuffer configuration for buffer!";
         return false;
         }
     return true;
@@ -558,12 +562,12 @@ bool SceneOpenGL::initDrawableConfigs()
         XFree( fbconfigs );
     if( fbcdrawableinfo[ DefaultDepth( display(), DefaultScreen( display())) ].fbconfig == NULL )
         {
-        kDebug( 1212 ) << "Couldn't find framebuffer configuration for default depth!";
+        kWarning( 1212 ) << "Couldn't find framebuffer configuration for default depth!";
         return false;
         }
     if( fbcdrawableinfo[ 32 ].fbconfig == NULL )
         {
-        kDebug( 1212 ) << "Couldn't find framebuffer configuration for depth 32!";
+        kWarning( 1212 ) << "Couldn't find framebuffer configuration for depth 32!";
         return false;
         }
     return true;
diff --git a/scene_xrender.cpp b/scene_xrender.cpp
index 6a20c537df..1169f63745 100644
--- a/scene_xrender.cpp
+++ b/scene_xrender.cpp
@@ -87,12 +87,12 @@ SceneXrender::SceneXrender( Workspace* ws )
     {
     if( !Extensions::renderAvailable())
         {
-        kDebug( 1212 ) << "No xrender extension available";
+        kWarning( 1212 ) << "No XRender extension available";
         return;
         }
     if( !Extensions::fixesRegionAvailable())
         {
-        kDebug( 1212 ) << "No xfixes v3+ extension available";
+        kWarning( 1212 ) << "No XFixes v3+ extension available";
         return;
         }
     KXErrorHandler xerr;
@@ -113,6 +113,8 @@ SceneXrender::SceneXrender( Workspace* ws )
         }
     createBuffer();
     init_ok = !xerr.error( true );
+    if( !init_ok )
+        kWarning( 1212 ) << "XRender compositing setup failed";
     }
 
 SceneXrender::~SceneXrender()