Laptop Sometimes Crashes When Close Lid to Sleep

Hello everyone, I have a really strange problem. My laptop's lid close action is set to sleep, although sometimes this isn't always successful. I own an HP Pavillion dv6tqe-7000. There's a light on the shell to indicate if the laptop is still on and at times when I close the lid the light continues to stay on meaning the laptop has not entered sleep mode. If I open the lid again the...