The files used by GNOME to associate the JAR and JNLP file extensions/mime-types can be left behind after all JRE/JDK RPM installations have been removed on Linux. This can occur if Tiger is installed on a system that also has 1.4.2 installed. It is caused by uninstalling Tiger, and then uninstalling 1.4.2. It does not occur if Tiger or a higher JRE/JDK version is the last version uninstalled.