When Launching an Extension Installer in Tiger Web Start, (or any double launch) the classpath is pass in with the args: "-classpath :/usr/jdk/jdk1.5.0/jre/lib/deploy.jar".
This extra seperator (not there in the native launch) causes the current directory to be in the class path. So If you have the class file to your current projects installer in the current directory, manually running "javaws InstallerTest.jnlp" will pick load the extension installer classes with the system ClassLoader, instead of the JNLPClassLoader, and so they can't be given all-permissions by the JNLPClassLoader.

This causes ExtensionInstallers to get AccessDenied exceptions even when they are fully signed and granted trust by the user.