diff --git a/MyTracks/src/com/google/android/apps/mytracks/content/TrackDataHub.java b/MyTracks/src/com/google/android/apps/mytracks/content/TrackDataHub.java
index 8ba075d6a..d596e4221 100644
--- a/MyTracks/src/com/google/android/apps/mytracks/content/TrackDataHub.java
+++ b/MyTracks/src/com/google/android/apps/mytracks/content/TrackDataHub.java
@@ -134,9 +134,10 @@ public class TrackDataHub implements DataSourceListener {
     started = false;
 
     dataSourceManager.unregisterAllListeners();
-    handlerThread.getLooper().quit();
-
-    handlerThread = null;
+    if (handlerThread != null) {
+      handlerThread.getLooper().quit();
+      handlerThread = null;
+    }
     handler = null;
     dataSource = null;
     dataSourceManager = null;
diff --git a/MyTracks/src/com/google/android/apps/mytracks/services/TrackRecordingService.java b/MyTracks/src/com/google/android/apps/mytracks/services/TrackRecordingService.java
index 78bff4bbc..6e49b2564 100644
--- a/MyTracks/src/com/google/android/apps/mytracks/services/TrackRecordingService.java
+++ b/MyTracks/src/com/google/android/apps/mytracks/services/TrackRecordingService.java
@@ -133,8 +133,9 @@ public class TrackRecordingService extends Service {
   private Location lastLocation;
   private boolean currentSegmentHasLocation;
 
-  // Timer to periodically invoke checkLocationListener
-  private final Timer timer = new Timer();
+  // TimerTask to register location listener
+  private TimerTask timerTask;
+  private Timer timer;
 
   // Handler for the timer to post a runnable to the main thread
   private final Handler handler = new Handler();
@@ -247,15 +248,6 @@ public class TrackRecordingService extends Service {
     }
   };
 
-  private TimerTask checkLocationListener = new TimerTask() {
-      @Override
-    public void run() {
-      if (isRecording() && !isPaused()) {
-        registerLocationListener();
-      }
-    }
-  };
-
   private final ConnectionCallbacks activityRecognitionCallbacks = new ConnectionCallbacks() {
       @Override
     public void onDisconnected() {}
@@ -301,10 +293,19 @@ public class TrackRecordingService extends Service {
     // onSharedPreferenceChanged might not set recordingTrackId.
     recordingTrackId = PreferencesUtils.RECORDING_TRACK_ID_DEFAULT;
 
-    // Require announcementExecutor and splitExecutor to be created.
+    // Require voiceExecutor and splitExecutor to be created.
     sharedPreferenceChangeListener.onSharedPreferenceChanged(sharedPreferences, null);
 
-    timer.schedule(checkLocationListener, 0, ONE_MINUTE);
+    timerTask = new TimerTask() {
+        @Override
+      public void run() {
+        if (isRecording() && !isPaused()) {
+          registerLocationListener();
+        }
+      }
+    };
+    timer = new Timer("TrackRecordingServiceTimer");
+    timer.schedule(timerTask, 0, ONE_MINUTE);
 
     /*
      * Try to restart the previous recording track in case the service has been
@@ -357,10 +358,15 @@ public class TrackRecordingService extends Service {
     showNotification(false);
 
     sharedPreferences.unregisterOnSharedPreferenceChangeListener(sharedPreferenceChangeListener);
-    checkLocationListener.cancel();
-    checkLocationListener = null;
-    timer.cancel();
-    timer.purge();
+    if (timerTask != null) {
+      timerTask.cancel();
+      timerTask = null;
+    }
+    if (timer != null) {
+      timer.cancel();
+      timer.purge();
+      timer = null;
+    }
     unregisterLocationListener();
 
     try {
diff --git a/MyTracks/src/com/google/android/apps/mytracks/services/sensors/SensorManager.java b/MyTracks/src/com/google/android/apps/mytracks/services/sensors/SensorManager.java
index 8b3787abf..36bcacde3 100644
--- a/MyTracks/src/com/google/android/apps/mytracks/services/sensors/SensorManager.java
+++ b/MyTracks/src/com/google/android/apps/mytracks/services/sensors/SensorManager.java
@@ -39,30 +39,8 @@ public abstract class SensorManager {
   private SensorState sensorState = SensorState.NONE;
   private long sensorStateTimestamp = System.currentTimeMillis();
 
-  /**
-   * A time task to check sensor connection.
-   */
-  private TimerTask checkSensorConnectionTimeTask = new TimerTask() {
-      @Override
-    public void run() {
-      switch (getSensorState()) {
-        case CONNECTING:
-          if (System.currentTimeMillis() - sensorStateTimestamp > MAX_SENSOR_STATE_AGE) {
-            Log.i(TAG, "Retry setUpChannel");
-            setUpChannel();
-          }
-          break;
-        case NONE:
-        case DISCONNECTED:
-          setUpChannel();
-          break;
-        default:
-          break;
-      }
-    }
-  };
-
-  private final Timer timer = new Timer();
+  private TimerTask timerTask;
+  private Timer timer;
 
   /**
    * Returns true if the sensor is enabled.
@@ -89,14 +67,43 @@ public abstract class SensorManager {
    */
   public void startSensor() {
     setUpChannel();
-    timer.schedule(checkSensorConnectionTimeTask, RETRY_PERIOD, RETRY_PERIOD);
+    timerTask = new TimerTask() {
+      @Override
+      public void run() {
+          switch (getSensorState()) {
+            case CONNECTING:
+              if (System.currentTimeMillis() - sensorStateTimestamp > MAX_SENSOR_STATE_AGE) {
+                Log.i(TAG, "Retry setUpChannel");
+                setUpChannel();
+              }
+              break;
+            case NONE:
+            case DISCONNECTED:
+              setUpChannel();
+              break;
+            default:
+              // CONNECTED or SENDING
+              break;
+          }
+      }
+    };    
+    timer = new Timer("SensorManagerTimer");
+    timer.schedule(timerTask, RETRY_PERIOD, RETRY_PERIOD);
   }
 
   /**
    * Stops the sensor.
    */
   public void stopSensor() {
-    timer.cancel();
+    if (timerTask != null) {
+      timerTask.cancel();
+      timerTask = null;
+    }
+    if (timer != null) {
+      timer.cancel();
+      timer.purge();
+      timer = null;
+    }
     tearDownChannel();
   }
 
diff --git a/MyTracks/src/com/google/android/apps/mytracks/services/tasks/TimerTaskExecutor.java b/MyTracks/src/com/google/android/apps/mytracks/services/tasks/TimerTaskExecutor.java
index bb542efc1..90021a233 100644
--- a/MyTracks/src/com/google/android/apps/mytracks/services/tasks/TimerTaskExecutor.java
+++ b/MyTracks/src/com/google/android/apps/mytracks/services/tasks/TimerTaskExecutor.java
@@ -68,7 +68,7 @@ public class TimerTaskExecutor {
         periodicTask.run(trackRecordingService);
       }
     };
-    timer = new Timer();
+    timer = new Timer("TimerTaskExecutorTimer");
     long next = System.currentTimeMillis() + interval - (tripStatistics.getTotalTime() % interval);
     timer.scheduleAtFixedRate(timerTask, new Date(next), interval);
   }