On my webclient there is this error.. which is this.

Code:
java.lang.ClassFormatError: Incompatible magic value 1008813135 in class file client
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClassCond(Unknown Source)
	at java.lang.ClassLoader.defineClass(Unknown Source)
	at java.security.SecureClassLoader.defineClass(Unknown Source)
	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)
Exception: java.lang.ClassFormatError: Incompatible magic value 1008813135 in class file client
I know what the problem is.. the problem is Incompatible magic value 1008813135 but I have no idea how to fix it.. I've tried several times and it still hasn't work.