NoClassDefFound puzzle

NoClassDefFound is my least favourite error message. This one has me
stumped. I have been very sick the last few days and my brain in not
yet fully engaged, so I hope it is something simple.

I compile this fine, but when I run it, it says class
com.mindprod.example.TestProgessFilter is not defined.
The program seems too simple to have a NoClassDefFound problem.

package com.mindprod.example;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

/**
 * @author Roedy Green, Canadian Mind Products
 * @version 1.0, 2007-08-03 Created with IntelliJ IDEA.
 */
public class TestProgessFilter extends FilterInputStream {

    /**
     * tracks how many bytes we have read so far
     */
    long progress;

    // -------------------------- PUBLIC INSTANCE METHODS
--------------------------
    /**
     * Constructor
     *
     * @param in input stream to progress monitor
     */
    public TestProgessFilter( InputStream in )
        {
        super( in );
        }

    /**
     * Reads the next byte of data from this input stream.
     */
    public int read() throws IOException
        {
        int ret = super.read();
        progress++;
        reportProgress();
        return ret;
        }

    /**
     * Reads up to byte.length bytes of data from this input stream
into an
     * array of bytes.
     */
    public int read( byte[] b ) throws IOException
        {
        int ret = super.read( b );
        progress += b.length;
        reportProgress();
        return ret;
        }

    /**
     * Reads up to len bytes of data from this input stream into an
array of
     * bytes.
     */
    public int read( byte[] b, int off, int len ) throws IOException
        {
        int ret = super.read( b, off, len );
        progress += len;
        reportProgress();
        return ret;
        }

    /**
     * Skips over and discards n bytes of data from this input stream.
*
     */
    public long skip( long n ) throws IOException
        {
        long ret = super.skip( n );
        progress += n;
        reportProgress();
        return ret;
        }

    // -------------------------- OTHER METHODS
--------------------------

    /**
     * report the progress to the user
     */
    private void reportProgress()
        {
        // this is a dummy routine. A real version would send an event
        // to a progress meter.
        System.out.println( progress );
        }

    // --------------------------- main() method
---------------------------
    /**
     * test driver
     *
     * @param args arg[0] is UTF-8 filename to read
     */
    public static void main( String args[] )
        {
        try
            {
            // O P E N
            FileInputStream fis = new FileInputStream( new File( args[
0 ] ) );
            TestProgessFilter tpfis = new TestProgessFilter( fis );
            InputStreamReader eisr = new InputStreamReader( tpfis,
"UTF-8" );
            BufferedReader br = new BufferedReader( eisr, 400/*
buffsize */ );

            // R E A D
            while ( true )
                {
                if ( br.readLine() == null )
                    {
                    // line == null means EOF
                    break;
                    }
                }

            // C L O S E
            br.close();
            }
        catch ( Exception e )
            {
            System.err.println( e );
            e.printStackTrace( System.err );
            }
        }
}
--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com