"Problem with Rapid Miner Installation Ubuntu: Cannot initialize XML serializatio"

Hi, I'm trying to run rapid miner on Ubuntu but anytime I try either the scripts or simply
java -jar lib/rapidminer.jar the program quits with the following message.

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G 28-Nov-08 10:17:36 AM: Property rapidminer.home is not set. Guessing.
G 28-Nov-08 10:17:36 AM: Trying parent directory of '/home/colin/rapidminer-4.3/lib/rapidminer.jar'...gotcha!
G 28-Nov-08 10:17:36 AM: Trying base directory of classes (build) 'failed
G 28-Nov-08 10:17:36 AM: ----------------------------------------------------
G 28-Nov-08 10:17:36 AM: Initialization Settings
G 28-Nov-08 10:17:36 AM: ----------------------------------------------------
G 28-Nov-08 10:17:36 AM: Default system encoding for IO: UTF-8
G 28-Nov-08 10:17:36 AM: Load core operators...
G 28-Nov-08 10:17:36 AM: Load Weka operators: true
G 28-Nov-08 10:17:36 AM: Load JDBC drivers from lib directory: true
G 28-Nov-08 10:17:36 AM: Load JDBC drivers from classpath: false
G 28-Nov-08 10:17:36 AM: Load plugins: true
G 28-Nov-08 10:17:36 AM: Load plugins from '/home/colin/rapidminer-4.3/lib/plugins'
G 28-Nov-08 10:17:36 AM: ----------------------------------------------------
G 28-Nov-08 10:17:36 AM: Read rcfile '/home/colin/rapidminer-4.3/etc/rapidminerrc'.
G 28-Nov-08 10:17:36 AM: Trying rcfile '/home/colin/rapidminer-4.3/etc/rapidminerrc.Linux'...skipped
G 28-Nov-08 10:17:36 AM: Trying rcfile '/home/colin/.rapidminer/4_3_0_rapidminerrc'...skipped
G 28-Nov-08 10:17:36 AM: Trying rcfile '/home/colin/.rapidminer/4_3_0_rapidminerrc.Linux'...skipped
G 28-Nov-08 10:17:36 AM: Trying rcfile '/home/colin/rapidminer-4.3/rapidminerrc'...skipped
G 28-Nov-08 10:17:36 AM: Trying rcfile '/home/colin/rapidminer-4.3/rapidminerrc.Linux'...skipped
G 28-Nov-08 10:17:36 AM: Trying rapidminer.rcfile. Property not specified...skipped
G 28-Nov-08 10:17:39 AM: Loading operators from 'operators.xml'.
G 28-Nov-08 10:17:52 AM: Loading JDBC driver information from 'etc:jdbc_properties.xml'.
G 28-Nov-08 10:17:52 AM: [Error] Cannot initialize XML serialization. Probably the libraries 'xstream.jar' and 'xpp.jar' were not provided. XML serialization will not work!
Exception in thread "main" java.security.InvalidParameterException: unsupported key size: 21
  at gnu.javax.crypto.jce.key.SecretKeyGeneratorImpl.engineInit(libgcj.so.81)
  at javax.crypto.KeyGenerator.init(libgcj.so.81)
  at com.rapidminer.tools.cipher.KeyGeneratorTool.createAndStoreKey(KeyGeneratorTool.java:66)
  at com.rapidminer.RapidMiner.init(RapidMiner.java:311)
  at com.rapidminer.RapidMiner.init(RapidMiner.java:228)
  at com.rapidminer.RapidMiner.init(RapidMiner.java:404)
  at com.rapidminer.gui.RapidMinerGUI.run(RapidMinerGUI.java:159)
  at com.rapidminer.gui.RapidMinerGUI.main(RapidMinerGUI.java:608)

xstream.jar and xpp3.jar are in the lib file.

any help on this would be appreciated,

Colin