Do not attempt to set null user images in tdm tdecontrol module
This resolves Bug 1899

diff --git a/kcontrol/tdm/tdm-users.cpp b/kcontrol/tdm/tdm-users.cpp
index d39d404..fe2f31c 100644
--- a/kcontrol/tdm/tdm-users.cpp
+++ b/kcontrol/tdm/tdm-users.cpp
@@ -263,7 +263,9 @@
 	p.load( m_userPixDir + ".default.face.icon" );
 	rstuserbutton->setEnabled( false );
     }
-    userbutton->setPixmap( p.smoothScale( 48, 48, TQ_ScaleMin ) );
+    if (!p.isNull()) {
+	    userbutton->setPixmap( p.smoothScale( 48, 48, TQ_ScaleMin ) );
+    }
 }