FULL PRODUCT VERSION :
JRE 1.4.2_17 and 1.6.0_10

ADDITIONAL OS VERSION INFORMATION :
Windows XP Pro SP2

EXTRA RELEVANT SYSTEM CONFIGURATION :
Windows is running as virtual image deployed under VMWare. Otherwise, is basic XP SP2 image. Version of Internet Explorer is 6.

A DESCRIPTION OF THE PROBLEM :
Machine starts with no Java VMs of any kind installed. Install JRE 1.4.2_17, run an applet successfully in Internet Explorer using OBJECT tag that uses dynamic version classid. Works fine.

Now install JRE 1.6.0_10. Adjust OBJECT tag to specify a "java_version" parameter with a value of "1.4*", which should select the latest JRE from the 1.4.x family. Try to run applet in IE, but applet fails to load. The 1.4.2_17 VM appears to start, as evidenced by the system tray icon whose pop-up menu says "Open 1.4.2_17 console". But attempting to open the console results in a console window with a gray panel in it.

Locating the trace file in the Application Data folder shows this exception and other info in the console:

java.lang.NoClassDefFoundError: sun/awt/DesktopBrowse
	at sun.plugin2.applet.Applet2Environment.initialize(Unknown Source)
	at sun.plugin2.main.client.PluginMain.handleMessageSetJVMID(Unknown Source)
	at sun.plugin2.main.client.PluginMain.mainLoop(Unknown Source)
	at sun.plugin2.main.client.PluginMain.run(Unknown Source)
	at sun.plugin2.main.client.PluginMain.main(Unknown Source)
security: property package.access value sun.
security: property package.access new value sun.,com.sun.javaws
security: property package.access value sun.,com.sun.javaws
security: property package.access new value sun.,com.sun.javaws,com.sun.deploy
security: property package.definition value null
security: property package.definition new value com.sun.javaws
security: property package.definition value com.sun.javaws
security: property package.definition new value com.sun.javaws,com.sun.deploy
security: property package.definition value com.sun.javaws,com.sun.deploy
security: property package.definition new value com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.access value sun.,com.sun.javaws,com.sun.deploy
security: property package.access new value sun.,com.sun.javaws,com.sun.deploy,org.mozilla.jss
security: property package.definition value com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.definition new value com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss

I've also tried using the backward compatible classid for specifying a JRE family (classid="clsid:CAFEEFAC-0014-0002-FFFF-ABCDEFFEDCBA"), but that has the same result.

The exception and symptoms are very similar to bug 6646549, which was closed as a "will not fix", with an evaluation stating that the exceptions are harmless.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Install 1.4.2_17 JRE on machine, then install 1.6.0_10. Create an HTML page with an OBJECT tag that uses java_version parameter to run applet in 1.4 family in Internet Explorer v6. Load applet page, but applet doesn't load.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Applet is expected to load and run using JRE 1.4.2_17, which is the latest JRE of the 1.4* family specified in the java_version parameter.
ACTUAL -
Applet does not load, exception appears in console trace:

java.lang.NoClassDefFoundError: sun/awt/DesktopBrowse
	at sun.plugin2.applet.Applet2Environment.initialize(Unknown Source)
	at sun.plugin2.main.client.PluginMain.handleMessageSetJVMID(Unknown Source)
	at sun.plugin2.main.client.PluginMain.mainLoop(Unknown Source)
	at sun.plugin2.main.client.PluginMain.run(Unknown Source)
	at sun.plugin2.main.client.PluginMain.main(Unknown Source)

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in console trace file:

java.lang.NoClassDefFoundError: sun/awt/DesktopBrowse
	at sun.plugin2.applet.Applet2Environment.initialize(Unknown Source)
	at sun.plugin2.main.client.PluginMain.handleMessageSetJVMID(Unknown Source)
	at sun.plugin2.main.client.PluginMain.mainLoop(Unknown Source)
	at sun.plugin2.main.client.PluginMain.run(Unknown Source)
	at sun.plugin2.main.client.PluginMain.main(Unknown Source)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
Applet code is unremarkable; just an applet that displays a panel with a label, showing the value of System.getProperty("java.version"). Applet source is compiled with -target 1.4 -source 1.4, though applet itself is not really specific to 1.4:


package test.ecl.applet;

import java.applet.Applet;
import java.awt.*;
import javax.swing.*;

public class Java14Applet extends Applet
{
	public void init()
	{
		System.out.println( "Java14Applet started" );
	}

	public void start()
	{
		JPanel panel = new JPanel();
		panel.setLayout( new BorderLayout() );
		panel.setSize( getSize() );
		JLabel label = new JLabel();

		String version = System.getProperty("java.version");
		if ( version.indexOf( "1.4" ) != -1 )
		{
			label.setText("Java14Applet running");
			label.setForeground( Color.blue );
		}
		else
		{
			label.setText( "Java14Applet requires Java 1.4! Found Java version: " + version );
			label.setForeground( Color.red );
		}
		panel.add( label, BorderLayout.CENTER );
		setLayout( new BorderLayout() );
		add( panel, BorderLayout.CENTER );
	}
}


HTML used to load the applet contains this:

<html>
<head>
<title>Java 1.4 applet</title>
</head>
<body>
<h3>Java 1.4 Applet with Object tag requiring 1.4.2</h3>
<object classid = "clsid:8AD9C840-044E-11D1-B3E9-00805F499D93"
    codebase = "http://java.sun.com/update/1.4.2/jinstall-1_4_2_17-windows-i586.cab#Version=1,4,0,0"
    width = "600"
    height = "400"
    name = "Java14Applet" >
    <PARAM NAME = "code" VALUE = "Java14Applet" >
    <PARAM NAME = "codebase" VALUE = "http://servername/session" >
    <PARAM NAME = "name" VALUE = "Java14Applet" >
    <param name="java_version" value="1.4*">
</object>
</body>
</html>

Alternative classid used to request 1.4.2 family JRE is:

classid="clsid:CAFEEFAC-0014-0002-FFFF-ABCDEFFEDCBA"

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

Release Regression From : 6u6
The above release value was the last known release where this 
bug was not reproducible. Since then there has been a regression.