static private Host maybeGetHost (String classname,USBListener startup_listener)
    throws IOException, SecurityException
    {
	try {
	    Object	temp;
	    HostFactory	factory;

	    temp = Class.forName (classname);
	    temp = ((Class)temp).newInstance ();
	    return ((HostFactory) temp).createHost (startup_listener);

	} catch (SecurityException e) {
	    throw e;

	} catch (IOException e) {
	    throw e;

	} catch (Exception e) {
	    return null;
	}
    }