###@###.###

The following test reproduces the problem:
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import java.awt.*;
import java.awt.event.*;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.io.InputStream;
import java.io.InputStreamReader;

public class ClipboardTest extends WindowAdapter {

    final Frame frame = new Frame();
    final Panel panel = new TestPanel();
    
    public static void main(String[] args) {
        ClipboardTest test = new ClipboardTest();
    }
     
    public ClipboardTest() {
        frame.setLayout(new FlowLayout());
        frame.add(panel);
        frame.pack();
        frame.addWindowListener(this);
        frame.setVisible(true);
    }
     
    public void windowClosing(WindowEvent e) {
        System.exit(0);
    }
}
 
class TestPanel extends Panel implements ActionListener {

    static final DataFlavor textFlavor =
        new DataFlavor("text/plain; class=java.io.InputStream", "Text");
        
    final Button button1 = new Button("Text Flavor");
    final Button button2 = new Button("String Flavor");
    final TextField textfield = new TextField();
    
    static Transferable transferable = null;
    
    TestPanel() {
        textfield.setEditable(false);
        button1.addActionListener(this);
        button2.addActionListener(this);
        
        setLayout(new GridLayout(3,1));
        add(textfield);
        add(button1);
        add(button2);
    }
     
    public void actionPerformed(ActionEvent e) {
        if (transferable == null) {
            transferable =
                Toolkit.getDefaultToolkit().getSystemClipboard().getContents(null);
        }
        if (e.getSource() == button1) {
            try {
                InputStream stream = (InputStream)transferable.getTransferData(textFlavor);
                InputStreamReader reader = new InputStreamReader(stream);
                StringBuffer buffer = new StringBuffer();
                for (int c = reader.read(); c != -1; c = reader.read()) {
                    buffer.append((char)c);
                }
                reader.close();
                textfield.setText(buffer.toString());
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        } else if (e.getSource() == button2) {
            try {
                String string = (String)transferable.getTransferData(DataFlavor.stringFlavor);
                textfield.setText(string);
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
    }
}
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Compile and run the test case.
The frame appears with a text field and two buttons.
Click both buttons several times.
Note that the text can be retrieved in text flavor
only once, while string flavor works correctly.
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Z:\bug\newbug>Z:\jdk1.4\win32\bin\java_g -version
java version "1.4.0beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0beta-b33)
Java HotSpot(TM) Client VM (build B22-debug, mixed mode)
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