diff --git a/MainWindow.xaml.cs b/MainWindow.xaml.cs
index 3414a2e..f9a3958 100644
--- a/MainWindow.xaml.cs
+++ b/MainWindow.xaml.cs
@@ -406,6 +406,7 @@ namespace GeekDesk
             {
                 MouseHookThread.Dispose();
             }
+            hide.TimerStop();
             Application.Current.Shutdown();
         }
 
diff --git a/Thread/MouseHookThread.cs b/Thread/MouseHookThread.cs
index 48d6f76..56eb57e 100644
--- a/Thread/MouseHookThread.cs
+++ b/Thread/MouseHookThread.cs
@@ -39,7 +39,9 @@ namespace GeekDesk.Thread
                 m_GlobalHook.MouseDownExt -= M_GlobalHook_MouseDownExt;
                 m_GlobalHook.Dispose();
                 dispatcher.InvokeShutdown();
-            } catch { }
+                dispatcher = null;
+            }
+            catch { }
             
         }
 
diff --git a/Util/MarginHide.cs b/Util/MarginHide.cs
index d6fe6ac..772f993 100644
--- a/Util/MarginHide.cs
+++ b/Util/MarginHide.cs
@@ -167,6 +167,7 @@ namespace GeekDesk.Util
 
         public void TimerStop()
         {
+            if (timer == null) return;
             timer.Stop();
             timer.Dispose();
             timer = null;