FULL PRODUCT VERSION :
java version "1.5.0_08"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_08-b03)
Java HotSpot(TM) Client VM (build 1.5.0_08-b03, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows 2000 [Version 5.00.2195]

Linux hun129ux 2.6.8-24-smp #1 SMP Wed Oct 6 09:16:23 UTC 2004 i686 i686 i386 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
deriveFont is not working with an instance of FontUIResource, which was instantiated with a dynamically loaded true type font.

PRECONDITION: the custom true type font specified in the createFont method must not be registered at the operating system level!

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a new font object by dynamically loading it from a file.
2. Create a new FontUIResource instance by passing it the font object created in the previous step.
3. Derive a new font object with deriveFont by, for example, changing the size. The deriveFont should be called on the FontUIResource instance created in the previous step.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The expected result should be a new font whose size has been changed as specified. The 'new font' here refers to the TTF loaded from the file.
ACTUAL -
Only the font size has changed, but the font is not what is loaded from the file.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.*;
import java.io.*;

/**
 * An application that demonstrates a JDK bug: deriveFont is not working with an
 * instance of FontUIResource, which was instantiated with a dynamically loaded
 * true type font. The true type font file must be located in the same folder where
 * the compiled class files of this program can be found.
 *
 * PRECONDITION: the custom true type font specified in the createFont method must not
 * be registered at the operating system level!
 */
public class BugDemonstrationPanel extends JPanel {
    static JFrame frame;
    private JLabel testLabel;
    private Font labelFont;
    public BugDemonstrationPanel() {
        InputStream fontStream =
            BugDemonstrationPanel.class.getResourceAsStream("<your TTF file name here>");
        if (fontStream != null) {
            try {
                labelFont = Font.createFont(Font.TRUETYPE_FONT, fontStream);
                labelFont = new FontUIResource(labelFont).deriveFont((float) 24);
                // If you use the next line instead of the previous one, everything works!
                // labelFont = labelFont.deriveFont((float) 24);
                System.out.println(labelFont.toString());
                fontStream.close();
            } catch (Exception e) {}
            testLabel = new JLabel();
            testLabel.setText("Only the font size changed, but not the font itself!");
            testLabel.setFont(labelFont);
            setSize(300, 200);
            add(testLabel);
}
    }

    public static void main(String s[]) {
        BugDemonstrationPanel panel = new BugDemonstrationPanel();
        frame = new JFrame(BugDemonstrationPanel.class.toString());
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
        });
        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
By not using the FontUIResource (as the demo code shows) everything works as expected.