XpcMessageLoop NullPointerException on soapUI 4.0/4.01 start

Hey guys,

Previous happy user of soapUI up to 3.61, recently upgraded to 4.0.0.

Running Fedora 14 x64, Oracle Java 1.6u21.

On start-up of soapui.sh I get the following exception in the console and the UI is completely unresponsive:

[developer@localhost bin]$ ./soapui.sh 
================================
=
= SOAPUI_HOME = /home/developer/soapui-4.0.1-SNAPSHOT
=
================================
Configuring log4j from [/home/developer/soapui-4.0.1-SNAPSHOT/bin/soapui-log4j.xml]
15:19:05,658 INFO  [DefaultSoapUICore] initialized soapui-settings from [/home/developer/soapui-4.0.1-SNAPSHOT/soapui-settings.xml]
15:19:07,077 INFO  [WorkspaceImpl] Loading workspace from [/home/developer/soapui-4.0.1-SNAPSHOT/bin/../../TestPBE-workspace.xml]
15:19:07,240 INFO  [WsdlProject] Loaded project from [file:/home/developer/soapui-projects/TBSB-soapui-project.xml]
15:19:08,626 INFO  [SoapUI] Used java version: 1.6.0_21
LoadPlugin: failed to initialize shared library libXt.so [libXt.so: cannot open shared object file: No such file or directory]
LoadPlugin: failed to initialize shared library libXext.so [libXext.so: cannot open shared object file: No such file or directory]
LoadPlugin: failed to initialize shared library /usr/lib/mozilla/plugins/nppdf.so [/usr/lib/mozilla/plugins/nppdf.so: wrong ELF class: ELFCLASS32]
LoadPlugin: failed to initialize shared library /usr/lib/flash-plugin/libflashplayer.so [/usr/lib/flash-plugin/libflashplayer.so: wrong ELF class: ELFCLASS32]
"Exception in thread "XpcMessageLoop" java.lang.NullPointerException
 at com.teamdev.xpcom.a.b.b.a(Unknown Source)
 at com.teamdev.xpcom.a.b.b.a(Unknown Source)
 at com.teamdev.xpcom.a.b.a$a.a(Unknown Source)
 at com.teamdev.xpcom.a.b.a$a.run(Unknown Source)
 at java.security.AccessController.doPrivileged(Native Method)
 at com.teamdev.xpcom.a.b.a.a(Unknown Source)
 at com.teamdev.xpcom.a.<init>(Unknown Source)
 at com.teamdev.xpcom.b$b.run(Unknown Source)

Looks similar to this 3.6.1 bug report: viewtopic.php?t=4370

Any help would be greatly appreciated.

All the best,

Pete