REGRESSION: web browser and java freeze when creating an JFileChooser object in applet

J2SE Version (please include all output from java -version flag):

java version "1.7.0_60-ea"
Java(TM) SE Runtime Environment (build 1.7.0_60-ea-b15)
Java HotSpot(TM) Client VM (build 24.60-b09, mixed mode, sharing)

Does this problem occur on J2SE 7ux? Yes / No (pick one)
  We detected the problem only with JRE7u60b15.


Operating System Configuration Information (be specific):
Windows 7 Ultimate - Service Pack 1 - 64bit
Web Browser - Any

Hardware Configuration Information (be specific):
Processor: Intel(R) Core(TM)2 Quad CPU Q8400 @2.66GHz 2.67GHz
RAM:4GB

Bug Description:

The problem occurs when running our applet with JAVA 7u60b15. Both, web browser and JAVA,
freeze when creating an JFileChooser object in our applet (as below).
 
JFileChooser fileChooser = new JFileChooser(); // this line causes Java to freeze
 
Not sure yet, but assume that the problem occurs when changing look and feel of the JFileChooser.
Everything goes well with JAVAu55 and JAVA1.8.0.20b11.
 
Steps to Reproduce (be specific):

1 - Install JAVA 7u60b15
2 - Acess the following site: https://www.ne2.bradesconetempresa.b.br/ibpjlogin/login.jsf?IPEmpresa=
3 - Select "Certificado Digital Bradesco".
4 - Press the "Procurar" button.

It should show a JFileChooser, but it freezes.