When i shutdown my laptop the screen shuts down but the power button still lights, :'( and i need to pres power button to shut it down :'( what to do ?

its the power button from where u can turn off the laptop.when i shut down my laptop no matter what os it is running the screen gets black showing its turned off but power button,fan and dvd rom still runs showing that it has power i have to shut it down by pressing the key for 5 seconds.help please why it does not completely shuts down???