Feb 8, 2011 8:37:36 PM org.bukkit.plugin.SimplePluginManager loadPlugins
SEVERE: Could not load plugins/Essentials.jar in plugins: null
org.bukkit.plugin.InvalidPluginException
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:66)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:117)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:82)
        at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:53)
        at net.minecraft.server.MinecraftServer.e(MinecraftServer.java:167)
        at net.minecraft.server.MinecraftServer.c(MinecraftServer.java:154)
        at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:106)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:202)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:512)
Caused by: java.util.zip.ZipException: error in opening zip file
        at java.util.zip.ZipFile.open(Native Method)
        at java.util.zip.ZipFile.<init>(ZipFile.java:114)
        at java.util.jar.JarFile.<init>(JarFile.java:135)
        at java.util.jar.JarFile.<init>(JarFile.java:99)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:53)
        ... 8 more
Feb 8, 2011 8:37:36 PM org.bukkit.craftbukkit.CraftServer loadPlugins
SEVERE: null (Is it up to date?)
java.lang.NullPointerException
        at org.bukkit.util.config.ConfigurationNode.getProperty(ConfigurationNode.java:33)
        at org.bukkit.util.config.ConfigurationNode.getList(ConfigurationNode.java:219)
        at org.bukkit.util.config.ConfigurationNode.getStringList(ConfigurationNode.java:242)
        at com.bukkit.lonelydime.DeathTpPlus.DeathTpPlus.onEnable(DeathTpPlus.java:58)
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:135)
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:405)
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:175)
        at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftServer.java:74)
        at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:55)
        at net.minecraft.server.MinecraftServer.e(MinecraftServer.java:167)
        at net.minecraft.server.MinecraftServer.c(MinecraftServer.java:154)
        at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:106)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:202)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:512)