On machines which do not have the Microsoft Visual Studio tools installed and which therefore do not have msvcr71.dll on the system search path, the new plug-in can not run applets on top of JDK 1.4.2 due to a dependency of its native code on msvcr71.dll. Here is a dump from the browser-side debugging code indicating the problem:

JRE 1.4.2.16: java.lang.UnsatisfiedLinkError: C:\Program Files\Java\jre6\bin\jp2native.dll: Can't find dependent libraries
JRE 1.4.2.16: at java.lang.ClassLoader$NativeLibrary.load(Native Method)
JRE 1.4.2.16: at java.lang.ClassLoader.loadLibrary0(Unknown Source)
JRE 1.4.2.16: at java.lang.ClassLoader.loadLibrary(Unknown Source)
JRE 1.4.2.16: at java.lang.Runtime.load0(Unknown Source)
JRE 1.4.2.16: at java.lang.System.load(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoading(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoadingFromJRE(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.load(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.os.windows.Windows.<clinit>(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.SystemUtil.computeIsVista(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.SystemUtil.getOSType(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.SystemUtil.formatNativeLibraryName(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoading(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoadingFromJRE(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.load(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.main.client.PluginMain.<clinit>(Unknown Source)
JRE 1.4.2.16: Exception in thread "main" JRE 1.4.2.16: java.lang.UnsatisfiedLinkError: C:\Program Files\Java\jre6\bin\jp2native.dll: Can't find dependent libraries
JRE 1.4.2.16: at java.lang.ClassLoader$NativeLibrary.load(Native Method)
JRE 1.4.2.16: at java.lang.ClassLoader.loadLibrary0(Unknown Source)
JRE 1.4.2.16: at java.lang.ClassLoader.loadLibrary(Unknown Source)
JRE 1.4.2.16: at java.lang.Runtime.load0(Unknown Source)
JRE 1.4.2.16: at java.lang.System.load(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoading(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoadingFromJRE(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.load(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.os.windows.Windows.<clinit>(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.SystemUtil.computeIsVista(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.SystemUtil.getOSType(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.SystemUtil.formatNativeLibraryName(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoading(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.tryLoadingFromJRE(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.util.NativeLibLoader.load(Unknown Source)
JRE 1.4.2.16: at sun.plugin2.main.client.PluginMain.<clinit>(Unknown Source)
JRE 1.4.2.16:
JRE 1.4.2.16: Exception in thread "main"
JVM instance for 1.4.2.16 exited