SecurityException in signed applet when opening JFileChooser with Java SE 6 update 25

Dear All,

We have an applet that opens a JFileChooser dialog at client side. It was working fine with Java SE version 6 update 23. Recently, the JRE was updated at the company to Java SE 6 Update 25. After this update, a SecurityException comes when users try to open the File Chooser. It appears but cannot be used.

The applet is signed and the app was not changed. The application invokes applet's File Chooser opening method through JavaScript. This means that when users click on the Browse button, it calls a JavaScript method which invokes the applet's File Chooser.

I've found the following bug on the web, but it says it is closed.
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7020285

Thank you in advance!
Akos