diff --git a/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/internal/provisional/ui/viewmodel/AbstractDebugVMAdapter.java b/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/internal/provisional/ui/viewmodel/AbstractDebugVMAdapter.java
index 11b0d1bd09d..49658a98dae 100644
--- a/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/internal/provisional/ui/viewmodel/AbstractDebugVMAdapter.java
+++ b/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/internal/provisional/ui/viewmodel/AbstractDebugVMAdapter.java
@@ -60,11 +60,13 @@ public class AbstractDebugVMAdapter extends AbstractDMVMAdapter
 
     @Override
     public void dispose() {
-        fController.getExecutor().execute(new DsfRunnable() {
-            public void run() {
-                fController.removeSteppingControlParticipant(AbstractDebugVMAdapter.this);
-            }
-        });
+    	if (!fController.getExecutor().isShutdown()) {
+	        fController.getExecutor().execute(new DsfRunnable() {
+	            public void run() {
+	                fController.removeSteppingControlParticipant(AbstractDebugVMAdapter.this);
+	            }
+	        });
+    	}
         super.dispose();
     }
 }
diff --git a/plugins/org.eclipse.dd.examples.pda.ui/src/org/eclipse/dd/examples/pda/ui/PDAAdapterFactory.java b/plugins/org.eclipse.dd.examples.pda.ui/src/org/eclipse/dd/examples/pda/ui/PDAAdapterFactory.java
index 9316f2511d7..679ccec448d 100644
--- a/plugins/org.eclipse.dd.examples.pda.ui/src/org/eclipse/dd/examples/pda/ui/PDAAdapterFactory.java
+++ b/plugins/org.eclipse.dd.examples.pda.ui/src/org/eclipse/dd/examples/pda/ui/PDAAdapterFactory.java
@@ -187,6 +187,10 @@ public class PDAAdapterFactory implements IAdapterFactory, ILaunchesListener2
 
         PDALaunch launch = (PDALaunch)adaptableObject;
 
+        // check for valid session
+        DsfSession session = launch.getSession();
+        if (session == null || !session.isActive()) return null;
+
         // Find the correct set of adapters based on the launch.  If not found
         // it means that we have a new launch, and we have to create a
         // new set of adapters.
diff --git a/plugins/org.eclipse.dd.gdb.ui/src/org/eclipse/dd/gdb/internal/ui/GdbAdapterFactory.java b/plugins/org.eclipse.dd.gdb.ui/src/org/eclipse/dd/gdb/internal/ui/GdbAdapterFactory.java
index 8a7abde4890..6645cb09f79 100644
--- a/plugins/org.eclipse.dd.gdb.ui/src/org/eclipse/dd/gdb/internal/ui/GdbAdapterFactory.java
+++ b/plugins/org.eclipse.dd.gdb.ui/src/org/eclipse/dd/gdb/internal/ui/GdbAdapterFactory.java
@@ -208,11 +208,13 @@ public class GdbAdapterFactory
 
         GdbLaunch launch = (GdbLaunch)adaptableObject;
 
+        // check for valid session
+        DsfSession session = launch.getSession();
+        if (session == null || !session.isActive()) return null;
+
         // Find the correct set of adapters based on the launch session-ID.  If not found
         // it means that we have a new launch and new session, and we have to create a
         // new set of adapters.
-        DsfSession session = launch.getSession();
-        if (session == null) return null;
 
         SessionAdapterSet adapterSet;
         synchronized(fgLaunchAdapterSets) {