Processing - setup issues on 64bit Ubunut 11.04

I downloaded Processing and got this error message when I tried to run it:

Exception in thread "main" java.lang.UnsatisfiedLinkError: /home/mindwave/processing-1.5.1/java/lib/i386/xawt/libmawt.so: libXtst.so.6: wrong ELF class: ELFCLASS64
 at java.lang.ClassLoader$NativeLibrary.load(Native Method)
 at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1803)
 at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1699)
 at java.lang.Runtime.load0(Runtime.java:770)
 at java.lang.System.load(System.java:1003)
 at java.lang.ClassLoader$NativeLibrary.load(Native Method)
 at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1803)
 at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1720)
 at java.lang.Runtime.loadLibrary0(Runtime.java:823)
 at java.lang.System.loadLibrary(System.java:1028)
 at sun.security.action.LoadLibraryAction.run(LoadLibraryAction.java:50)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.awt.Toolkit.loadLibraries(Toolkit.java:1605)
 at java.awt.Toolkit.<clinit>(Toolkit.java:1627)
 at processing.app.Base.<clinit>(Base.java:445)
Could not find the main class: processing.app.Base.  Program will exit.


I am running Ubuntu 11.10 64 bit, and was attempting to run Processing 1.5.1 from this tarball: http://processing.googlecode.com/files/processing-1.5.1-linux.tgz

Bug tracker: http://code.google.com/p/processing/issues/detail?id=717