not sure why but there is an error?

Java Plug-in 1.6.0_20
Using JRE version 1.6.0_20-b02 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\
----------------------------------------------------
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
----------------------------------------------------


java.lang.reflect.InvocationTargetException
at java.awt.EventQueue.invokeAndWait(Unknown Source)
at javax.swing.SwingUtilities.invokeAndWait(Unknown Source)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationView.(LinearEquationView.java:188)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationSimulation.(LinearEquationSimulation.java:20)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquation.(LinearEquation.java:93)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationApplet.init(LinearEquationApplet.java:26)
at sun.plugin2.applet.Plugin2ManagerAppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.security.AccessControlException: access denied (java.net.SocketPermission www.moe.gov.sg resolve)
at java.security.AccessControlContext.checkPermission(Unknown Source)
at java.security.AccessController.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkConnect(Unknown Source)
at sun.plugin2.applet.Applet2SecurityManager.checkConnect(Unknown Source)
at sun.awt.SunToolkit.getImageFromHash(Unknown Source)
at sun.awt.SunToolkit.getImage(Unknown Source)
at javax.swing.ImageIcon.(Unknown Source)
at javax.swing.ImageIcon.(Unknown Source)
at org.opensourcephysics.tools.ResourceLoader.getIcon(Unknown Source)
at org.colos.ejs.library.control.swing.ControlSwingElement.getIcon(Unknown Source)
at org.colos.ejs.library.control.swing.ControlMenuItem.setValue(Unknown Source)
at org.colos.ejs.library.control.ControlElement.setProperty(Unknown Source)
at org.colos.ejs.library.control.ControlElement.setProperty(Unknown Source)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationView.createControl50(LinearEquationView.java:1360)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationView.createControl(LinearEquationView.java:1206)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationView.access000(LinearEquationView.java:19)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationView1.run(LinearEquationView.java:190)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
java.lang.NullPointerException
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationView.reset(LinearEquationView.java:1653)
at org.colos.ejs.library.Animation.reset(Unknown Source)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationSimulation.(LinearEquationSimulation.java:24)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquation.(LinearEquation.java:93)
at users.sgeducation.lookang.LinearEquation_pkg.LinearEquationApplet.init(LinearEquationApplet.java:26)
at sun.plugin2.applet.Plugin2ManagerAppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception: java.lang.NullPointerException