java blocked by security

[Andre Hübner]

Ubuntu 8.04.3 LTS

Hello List,

i istalled sun-java5-bin, sun-java5-jre and libjline-java.
I want to run a .jar file which is only successful when running as root.
If i start the file in user-environment i got following error:

Exception in thread "main" java.lang.NoClassDefFoundError

at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:336)
Could not find the main class
. Program will exit.

i assume some internal security-settings in java because file should be ok 
which is demonstrated when starting as root.
Where could be a java-related option  to let java-programm run in 
user-environment?

Thanks,
Andre