diff --git a/XenAdmin/Controls/MainWindowControls/NavigationView.cs b/XenAdmin/Controls/MainWindowControls/NavigationView.cs
index ae7e2d49a..7ccfb258a 100644
--- a/XenAdmin/Controls/MainWindowControls/NavigationView.cs
+++ b/XenAdmin/Controls/MainWindowControls/NavigationView.cs
@@ -337,6 +337,9 @@ namespace XenAdmin.Controls.MainWindowControls
 
         private void RefreshTreeView()
         {
+            if (Disposing || IsDisposed || Program.Exiting)
+                return;
+
             Program.Invoke(this, () =>
             {
                 if (ignoreRefreshTreeView > 0)
diff --git a/XenAdmin/Program.cs b/XenAdmin/Program.cs
index 6d4e15164..52abb02ea 100644
--- a/XenAdmin/Program.cs
+++ b/XenAdmin/Program.cs
@@ -596,8 +596,8 @@ namespace XenAdmin
                            Messages.MESSAGEBOX_PROGRAM_UNEXPECTED_TITLE));
 
                     // CA-44733
-                    if (Program.MainWindow != null && !Program.MainWindow.InvokeRequired)
-                        d.ShowDialog(Program.MainWindow);
+                    if (MainWindow != null && !IsExiting(MainWindow) && !MainWindow.InvokeRequired)
+                        d.ShowDialog(MainWindow);
                     else
                         d.ShowDialog();
                 }