diff --git a/src/main/java/edu/mit/blocks/workspace/ContextMenu.java b/src/main/java/edu/mit/blocks/workspace/ContextMenu.java
index 147bc016f90add28c225222b4366dfc78f5dda46..ce95f2ba45b7a7712484e710f54ed24b461737a8 100644
--- a/src/main/java/edu/mit/blocks/workspace/ContextMenu.java
+++ b/src/main/java/edu/mit/blocks/workspace/ContextMenu.java
@@ -195,7 +195,7 @@ public class ContextMenu extends PopupMenu implements ActionListener {
     	
     	System.out.println("TEST | Active Block: "+blockGenusName);
     	
-    	//TODO: call 404.html when there is no reference-file for active block
+    	//TODO: TEST on all plattforms (Linux/MAC/Windows)
 		try {
 			Desktop.getDesktop().browse(getClass().getResource(resourcePath).toURI());
 		} catch (IOException e) {
@@ -205,7 +205,16 @@ public class ContextMenu extends PopupMenu implements ActionListener {
 			// TODO Auto-generated catch block
 			e.printStackTrace();
 		} catch (NullPointerException e) {
-			e.printStackTrace();
+			//e.printStackTrace();
+			try {
+				Desktop.getDesktop().browse(getClass().getResource("/com/ardublock/reference/404.html").toURI());
+			} catch (IOException e1) {
+				// TODO Auto-generated catch block
+				e1.printStackTrace();
+			} catch (URISyntaxException e1) {
+				// TODO Auto-generated catch block
+				e1.printStackTrace();
+			}
 		}
 		
 		/*