Hi,
looks like you are using the gnu-gcj version of java which gives you this error.
There is a command on the eeepc-OS that lets you switch to the Java-Runtime from Sun which is also installed on the eeepc by default. Open a terminal (Ctrl-Alt-T) and list the options for java
/home/user> sudo update-java-alternatives -l
java-1.5.0-sun 53 /usr/lib/jvm/java-1.5.0-sun
The following should switch to the sun-runtime
/home/user> sudo update-java-alternatives -s java-1.5.0-sun
Please report back if that works for you so we can update the playground-article
Eberhard