Some restrictions may apply to the way you set CLASSPATH if you use Firefox.
The Java Virtual Machine (JVM) security manager does not allow a version of SAP jConnect installed in your local file system to create a connection to a server, even if the server is your local system. This can create a problem if you use Firefox to run an applet that uses SAP jConnect.
When Firefox loads SAP jConnect to connect to a server, it looks at CLASSPATH to find the SAP jConnect classes. If it finds a path that points to your local SAP jConnect installation, it loads SAP jConnect directly from the local file system rather than from the server and tries to create a connection. This generates a security error and the connection fails.
Do not include the local SAP jConnect directory in CLASSPATH if you are using Firefox to run SAP jConnect applets.