Not able to debug simple hello world program

Hi all,
I am a biginner to java programming and eclipse.
I wrote a simple helloworld program as follows:

package hello;

public class Hello {
public static void main(String args[]){
System.out.println("Hello World");
}

}

The program runs successfully and gives the output to the console:
Hello World

I double clicked the line with println to add a break point. But when i press F11 to Debug the program the debug view shows the following error:
Hello [Java Application]
hello.Hello at localhost:35874
Thread [main] (Suspended (exception ClassNotFoundException))
ClassLoader.findBootstrapClass(String) line: not available [native method]
Launcher$ExtClassLoader(ClassLoader).findBootstrap Class0(String) line: not available
Launcher$ExtClassLoader(ClassLoader).loadClass(Str ing, boolean) line: not available
Launcher$AppClassLoader(ClassLoader).loadClass(Str ing, boolean) line: not available
Launcher$AppClassLoader.loadClass(String, boolean) line: not available
Launcher$AppClassLoader(ClassLoader).loadClass(Str ing) line: not available
Launcher$AppClassLoader(ClassLoader).loadClassInte rnal(String) line: not available
/usr/java/jre1.6.0_05/bin/java (Jun 12, 2008 6:29:20 PM)

The error shows: Source not found.

Please help me to solve this problem.

Thanks in advance