Uno can read my data sent from Vista computer but not from Windows 8 computer

I have a Hewlett Packard dx2300 computer with Vista Service Pack 2, 32 bits, and Intel processor.
I also have a Toshiba Satellite C850D-11C computer with Windows 8, 64 bits and AMD processor.
Both computers can load, and run example programs like "Blink" to my Arduino Uno. No problems with that.
I have made a Java program that sends data to Arduino Uno via USB cable. Four of UNO's
output pins are connected to a AD9850 Direct Digital Synthesis (DDS) that is working as local
oscillator in my my home made shortwave receiver.
The program is functioning ok when I use the HP computer that has 32 bits Vista.
When I use the Toshiba computer with Windows 8 the program does not work.

How I start the UNO and the Java program:
The computer and UNO are connected to each other with an USB cable.
I start the Arduino 1.0.5 program.
Then I open the Serial Monitor window.
Then I close the Serial Monitor window.
Then I turn on the power to the DDS.
Then I start my Java Program in the computer.

If the computer is my HP computer I can now set the frequency of the DDS signal as I like.
The RX LED in UNO lights each time when I change the frequency by pushing arrow keys on the computer.

If the computer is my Toshiba computer nothing happens to the DDS and the RX LED does not light when I
try to change the frequency. Instead a file named COM11 is created.

This is the program in UNO:

/* Rx0_9600
Sets the frequency of DDS for my radio receiver.
Gets data from Java-program RxFreq3.java
*/

byte myPins[] = {6, 7, 9, 3};

void setup() {
  byte BlackLed = 13;
  pinMode(BlackLed, OUTPUT);
  digitalWrite(BlackLed, LOW);
  Serial.begin(9600);  
  for(int i = 0; i < 4; i++)
    pinMode(myPins[i], OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly: 
  if (Serial.available() == 1) {
  byte bitt;
  bitt = Serial.read(); 
  for(int i = 0; i < 4; i++){    
    digitalWrite(myPins[i], bitRead(bitt, i));
    }
  }
}

End of UNO program.

The part of the Java program that writes to the COM port looks like this:

               try 
               {
                  FileOutputStream ff = new FileOutputStream(RxFreq3.comName); //HP: comName is COM4, Toshiba: comName is COM11
                  for (int ii=0; ii<135; ii++){
                     ff.write(frUpdateClockDataMKL[ii]);
                     BDelay2.bDelay2(RxFreq3.delay, 0); // bDelay, makes 1 millisecond delay
                  }
                  ff.close();        
               }
               catch (IOException e)
               {
                  System.out.println("Error " + e.toString());
               }

End of Java part that writes to COM port.

Moderator edit:
</mark> <mark>[code]</mark> <mark>

</mark> <mark>[/code]</mark> <mark>
tags added.

What are the CPU speeds of the 2 PC's?

Are you getting an output on stderr?

Do you get a reset on connecting the comms port?

Do you have the right comms ports?

Do you have the right default settings for the comms port?

What happens if you just use the serial monitor. Can you talk to a simple echo sketch?

Mark

What data is the Java application actually writing to the virtual serial port?

Given that you seem to have a fundamental problem, I suggest you write a sketch that merely reads from the serial port and sends back an acknowledgment for each character received. Use the Arduino serial monitor to send text to it and confirm that you get the expected output.

If that fails, it's a probably problem with the USB drivers or serial port settings.

If it succeeds, you have a communication problem that could be caused by either the Java app or the Arduino sketch, and we can look into it further to find out which.

If I were you, I will first install latest version of Arduino IDE at Windows 8 machine, Start from Arduino IDE 1.0.5 come with Windows signed drivers. This means Windows 8 will no longer prevent you from installing Arduino drivers. after that test IDE and make sure it work.

Please put code into code tag, It will make every one eye happy.