Signed Applet to write on LPT1 port - permission error

[ConvoyTh]

Hi,
I have a simple applet based on this code:

import java.awt.*;
import java.applet.*;
import java.util.*;
import java.io.*;
 
public class TestJavaXp extends Applet{
	int i = 0;
	String s = "Print this text";
	    try {
		FileWriter out = new FileWriter("LPT1");
		out.write(s);	
		out.flush();
		out.close();      
		}
	    catch (IOException e) {
		e.printStackTrace();
		}
}

I signed the applet, I accepted the certification pop-up, but I receive this error:
uncaught exception: Error calling method on NPObject!
[plugin exception: java.security.AccessControlException: access denied (java.ioFilePermission LPT1 write)]

It works perfectly only if I grant permissions in the java.policies file, but I can't always do it of course.

Why?
I've no problem signing applets that write files on disk, I've troubles only with LPT1 port but I need it.
I tried different browsers (Firefox 3, Chrome 2, IE7).

Can anyone help me?

Thanks.