Arduino Uno as a HID Keyboard PROBLEM

Hi.

I still have not figured out what is going on.

Once I add counter to the code it will start to send random keys to the PC:
If I use one button to send one Symbol it works.

Is there another way to send numbers from 0 to 9 (or some other keys) without using Counter?
I have tried that random key press works fine.

Anyideas how to use it?

/* Arduino USB HID Keyboard Demo
 * Random Key/Random Delay
 */
 
uint8_t buf[8] = { 
  0 }; 	/* Keyboard report buffer */
 
void setup() 
{
  Serial.begin(9600);
  randomSeed(analogRead(0));
  delay(200);
}
 
void loop() 
{
  int randomChar = random(4, 130);
  long randomDelay = random(1000, 10000);
 
  delay(randomDelay);
 
  buf[2] = randomChar;	  // Random character
  Serial.write(buf, 8);	// Send keypress
  releaseKey();
}
 
void releaseKey() 
{
  buf[0] = 0;
  buf[2] = 0;
  Serial.write(buf, 8);	// Release key  
}