--- core/graphviz_api.php	2004-10-08 23:08:35.698529016 -0300
+++ core/graphviz_api.php	2004-10-08 23:13:24.448632328 -0300
@@ -270,6 +270,13 @@
 				# If we are under Windows, we use the COM interface provided
 				# by WinGraphviz. Thanks Paul!
 
+				# Issue #4625: Work around WinGraphviz bug that fails with
+				# graphs with zero or one node. It is probably too much to
+				# generate a graphic output just to explain it to the user,
+				# so we just return a null content.
+				if ( count( $this->nodes ) <= 1 )
+					return;
+
 				$t_graphviz = new COM( $this->graphviz_com_module );
 
 				# Check if we managed to instantiate the COM object.