Messages.showMessageDialog is crashing the IDE !

Hi ! I was fighting with this for hours and I don't know how to solve it.
Can you tell me if there is something wrong with this code?

    public static void showDialog(final String message, final String title, final Icon icon)
    {

        UIUtil.invokeAndWaitIfNeeded(new Runnable() {
            @Override
            public void run() {

                    Messages.showMessageDialog(message, title, icon);

            }
        });

    }

The IDE shows the dialog but I can't close it, even more, I can't close the IDE ! (I need to kill the process, I'm using Windows).
This happens when I execute showDialog from my Code Completion Contributor.

Any help is really welcome.

Thanks !