Serialization of some classes (FILE, URL etc) throws exception.

-------- Test.java ---------
import java.io.*;

class Test implements java.io.Serializable {
    public static void main (String argv[]) {

      try {
FileOutputStream ostream = new FileOutputStream("t.tmp");
ObjectOutputStream p = new ObjectOutputStream(ostream);
 
p.writeInt(12345);
p.writeObject("Today");
p.writeObject(new File("Test.java"));
 
p.flush();
ostream.close();
      }
      catch (Exception e) {
e.printStackTrace();
      }

    }
}
------------------------------

% java -version
java version "1.4.0beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0beta-b42)
Java HotSpot(TM) Client VM (build 1.4beta-B42, mixed mode)

% java Test
Exception in thread "main" java.lang.InternalError: Unable to access writeObject method
        at java.io.ObjectOutputStream.invokeObjectWriter(ObjectOutputStream.java:1895)
        at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1210)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:366)
        at Test.main(Test.java:12)

--------------
Fails in build B-42. Works fine with build-B41