License installation crashes SoapUI Pro 3.0 on Ubuntu

Hi,

I am running Ubuntu 9.04 with Sun JDK 1.6.0_14. Trying to run SoapUI Pro 3.0 (ZIP version). When importing the license:

The program 'TuxPack GTK+' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadWindow (invalid Window parameter)'.
  (Details: serial 3228 error_code 3 request_code 20 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
  that is, you will receive the error a while after causing it.
  To debug your program, run it with the --sync command line
  option to change this behavior. You can then get a meaningful
  backtrace from your debugger if you break on the gdk_x_error() function.)


Best regards,

Phil