logcatからはかれたエラーの意味がわからない

Question

今、EclipseでAndroidアプリの開発をしているんですが、デバッグすると、logcatにこのエラーが出ました。

なぜなのでしょうか？

以下、エラー内容
E/Trace(658): error opening trace file: No such file or directory (2)
W/ActivityThread(658): Application notify.sleepnotification is waiting for the debugger on port 8100...
I/System.out(658): Sending WAIT chunk
I/dalvikvm(658): Debugger is active
I/System.out(658): Debugger has connected
I/System.out(658): waiting for debugger to settle...
I/System.out(658): waiting for debugger to settle...
I/System.out(658): waiting for debugger to settle...
I/System.out(658): waiting for debugger to settle...
I/System.out(658): waiting for debugger to settle...
I/System.out(658): waiting for debugger to settle...
I/System.out(658): waiting for debugger to settle...
02-02 15:05:25.872: I/System.out(658): waiting for debugger to settle...
I/System.out(658): waiting for debugger to settle...
I/System.out(658): debugger has settled (1409)
D/AndroidRuntime(658): Shutting down VM
W/dalvikvm(658): threadid=1: thread exiting with uncaught exception (group=0x40a122a0)
E/AndroidRuntime(658): FATAL EXCEPTION: main
E/AndroidRuntime(658): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{notify.sleepnotification/notify.sleepnotification.MainActivity}: java.lang.ClassNotFoundException: notify.sleepnotification.MainActivity
E/AndroidRuntime(658): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
E/AndroidRuntime(658): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
E/AndroidRuntime(658): at android.app.ActivityThread.access$600(ActivityThread.java:130)
E/AndroidRuntime(658): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
E/AndroidRuntime(658): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(658): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(658): at android.app.ActivityThread.main(ActivityThread.java:4745)
E/AndroidRuntime(658): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(658): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(658): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
E/AndroidRuntime(658): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
E/AndroidRuntime(658): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(658): Caused by: java.lang.ClassNotFoundException: notify.sleepnotification.MainActivity
E/AndroidRuntime(658): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
E/AndroidRuntime(658): at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
E/AndroidRuntime(658): at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
E/AndroidRuntime(658): at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
E/AndroidRuntime(658): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
E/AndroidRuntime(658): ... 11 more