Backlight problem

Sometimes when I put the Air in sleep mode, when I open it the backlight does not come back on. I can see the outline of my windows but there is no light. I can't get it to come on by pressing keys, using the trackpad, or prssing the power button once. I usually am forced to hold down the power button to shut down the computer. I know this is bad for the laptop and I already had to have the hard drive replaced - they did not say why. How can I get the backlight to come on in these circumstances, and if I can't, is there an alternative way to shut down? Should I contact Apple Care regarding this issue?