New to Java

After the installation of Java 5 I receive always the following error report:
Thanks for any help.

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Dokumente und Einstellungen\Frei.SATAGARBON>javac -version
javac 1.5.0_04
javac: no source files
:
:
C:\Dokumente und Einstellungen\Frei.SATAGARBON\Desktop>javac HalloWelt.java
An exception has occurred in the compiler (1.5.0_04). Please file a bug at the J
ava Developer Connection (http://java.sun.com/webapps/bugreport) after checking
the Bug Parade for duplicates. Include your program and the following diagnosti
c in your report. Thank you.
java.lang.ClassFormatError: Unknown constant tag 0 in class file com/sun/tools/j
avac/comp/Check
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:12
4)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
at com.sun.tools.javac.code.Types.<init>(Types.java:60)
at com.sun.tools.javac.code.Types.instance(Types.java:49)
at com.sun.tools.javac.jvm.ClassReader.<init>(ClassReader.java:192)
at com.sun.tools.javac.jvm.ClassReader.instance(ClassReader.java:153)
at com.sun.tools.javac.main.JavaCompiler.<init>(JavaCompiler.java:131)
at com.sun.tools.javac.main.JavaCompiler.instance(JavaCompiler.java:46)
at com.sun.tools.javac.main.Main.compile(Main.java:589)
at com.sun.tools.javac.main.Main.compile(Main.java:544)
at com.sun.tools.javac.Main.compile(Main.java:67)
at com.sun.tools.javac.Main.main(Main.java:52)