diff --git a/csl.api/src/org/netbeans/modules/csl/navigation/ElementNode.java b/csl.api/src/org/netbeans/modules/csl/navigation/ElementNode.java
--- a/csl.api/src/org/netbeans/modules/csl/navigation/ElementNode.java
+++ b/csl.api/src/org/netbeans/modules/csl/navigation/ElementNode.java
@@ -545,7 +545,7 @@
             
             synchronized (this) {
                 this.parentItem = description;
-                if (processing == 0) {
+                if (!initialized && processing == 0) {
                     return null;
                 }
                 items = snapshot();
@@ -791,7 +791,7 @@
     }
     
     public static boolean isWaitNode(Node n) {
-        return n.getLookup().lookup(WaitNode.class) != null;
+        return n != null && n.getLookup().lookup(WaitNode.class) != null;
     }
     
     public static boolean isWaitNode(StructureItem si) {
diff --git a/csl.api/src/org/netbeans/modules/csl/navigation/TreeUpdater.java b/csl.api/src/org/netbeans/modules/csl/navigation/TreeUpdater.java
--- a/csl.api/src/org/netbeans/modules/csl/navigation/TreeUpdater.java
+++ b/csl.api/src/org/netbeans/modules/csl/navigation/TreeUpdater.java
@@ -46,6 +46,7 @@
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -77,13 +78,13 @@
      */
     private boolean     waiting;
     
-    private List<Node>  nodesToExpand;
+    private final List<Node>  nodesToExpand = new LinkedList<Node>();
     
-    private List<Node>  nodesToExpandRec;
+    private final List<Node>  nodesToExpandRec = new LinkedList<Node>();
     
     private List<UpdateRecord>  childrenToUpdate;
     
-    private List<UpdateRecord>  newChildren;
+    private List<UpdateRecord>  newChildren = new ArrayList<UpdateRecord>();
 
     public TreeUpdater(ClassMemberPanelUI ui) {
         this.ui = ui;