Why the watchdog at Arduino works wrong?

Projects Programming
2

The watchdog timer works fine on my Arduino UNO R2 with the latest bootloader from Arduino 1.0. Have you tried burning a fresh bootloader?

//  Watchdog Timer Example
#include <avr/wdt.h>

unsigned long ToggleDelay;  //  When this delay grows to longer than the WDT interval the WDT resets the Arduino

const int LEDpin = 13;

void toggle_led()
{
  digitalWrite(LEDpin, !digitalRead(LEDpin));
}

void setup()
{
  wdt_disable();
  ToggleDelay = 1;   // Start with a very short delay
  pinMode(LEDpin, OUTPUT);
  wdt_enable(WDTO_250MS);  // Set watchdog to 1/4 second
}

void loop()
{
  wdt_reset();
  toggle_led();   // Blinking goes slower and slower until the WDT causes reset, then starts over.
  delay(ToggleDelay);
  ToggleDelay += 5;   // Increase the delay by 5 milliseconds.
}