Error in starting new activity using Intent in android

I have created a menu for my android application. The menu has several buttons, The first buttons should start new Activity called "BackgroundImages" using Intent. However, When I install the app on the emulator and click the button, I receive the following error "Unfortunatlry, NewtonLow has stopped".Moreover, "NewtonLow" is the name of the application. The following demonstrates the steps I did in order to start new Activity.

1. I created a class called Menu which display the the menu.xml layout as follows:

   public class Menu extends Activity{
   
      MediaPlayer mp1;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       // TODO Auto-generated method stub
       super.onCreate(savedInstanceState);
       setContentView(R.layout.menu);  
       mp1= MediaPlayer.create(this,R.raw.button );
       Button but1 =  (Button)findViewById(R.id.button1);
       but1.setOnClickListener(new View.OnClickListener() {            
           @Override
           public void onClick(View v) {
               // TODO Auto-generated method stub
               mp1.start();
               startActivity(new Intent("ghassar.mohamed.newtonlaw.BACKGROUNDIMAGES"));
           }
       });
   }}
   
   

2. I have edited the Manifast to launch the menu class first as follows:

       <activity
       android:name=".Menu"
       android:label="@string/app_name" >
       <intent-filter>
           <action android:name="android.intent.action.MAIN" />
           <category android:name="android.intent.category.LAUNCHER" />
       </intent-filter>
   </activity>
   
   

   3. I have also added activity for the backgroundImage class to use it so I can I can start the activity :

              <activity android:name=".BackgroundImages"android:label="@string/app_name" >
      <intent-filter>
          <action android:name="ghassar.mohamed.newtonlaw.BACKGROUNDIMAGES" />
          <category android:name="android.intent.category.DEFUALT" />
      </intent-filter>