runescape error

hey, i'm hoping someone can help me.

ive played runescape for a pretty long time but every time i try to get on now it gives me this error message. it says error click for details. so i click it and it says...

Java Plug-in 1.6.0_18
Using JRE version 1.6.0_18-b07 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\Jenny Clark
----------------------------------------------------
c: clear console window
f: finalize objects on finalization queue
g: garbage collect
h: display this help message
l: dump classloader list
m: print memory usage
o: trigger logging
q: hide console
r: reload policy configuration
s: dump system and deployment properties
t: dump thread list
v: dump thread stack
x: clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------


load: class loader.class not found.
java.lang.ClassNotFoundException: loader.class
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: open HTTP connection failed:http://world161.runescape.com/loader/class.class
at sun.plugin2.applet.Applet2ClassLoader.getBytes(Unknown Source)
at sun.plugin2.applet.Applet2ClassLoader.access$000(Unknown Source)
at sun.plugin2.applet.Applet2ClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
... 7 more
Exception: java.lang.ClassNotFoundException: loader.class

i have no idea what any of this means and i would appreciate it alot if someone could explain and tell me how to fix this problem.
Thanks alot

What's your OS?
Make sure your account has admin rights.

If that doesn't work, try uninstalling and re-download the latest java runtime.

Ok lets think of other possible solutions:

Try disabling your firewall completely.
Did it work?
If not, try this:
Open your java console (right click the java icon on the system tray and select open console) when the error appears and press the s key to dump system proprieties .
_

If it didn't work:
Open java control panel.
In the General tab, where it says Temporary Internet Files, select Settings.
On the new windows select "Restore Defaults" and then press "Delete Files".
This will delete all files downloaded from any java application.

Next:
If you're using windows: Go to your windows folder C:\Windows and locate the folder .jagex_cache_32
Delete the folder ".jagex_cache_32" and all the files inside it.

There's another file you could try to delete, called jagex_preferences.dat but i'm not sure where it stays in XP or 7 since I'm on Vista at the moment.
On Vista its located on your Default document folder.

Now, try runescape again.

Just want to be careful with that firewall disabled, bad things can come of it.

Yes agreed. Now that we found out that the firewall is the problem, we should see what's causing it.
Its a very important component that protects you from almost all threats, hackers, etc.
Turn your firewall back on, but this time check if its allowing java to connect. Which firewall do you use?

That security center doesn't sound very appealing to me.
Consider changing anti-virus and firewall.
I'd strongly recommend Comodo Internet Security.
Its free and one of the best firewalls out there.
Can be a little annoying at the start, but it will learn your preferences through time.