This is not a security issue and has nothing to do with the descriptors. The error simply means that your client does not have the com.mspsn.genps.spielkonfigurationHome classes in its classpath. The security manager issue is RMI attempting to download the classes from the server, but this only occurs when a Java2 security manager is active. Just fix your classpath.
you're right. That was the problem. Thank you very much!