SGS3 GT-I9305 lockscreen problem

[alphonsus2010]

Sometimes when i screen off my phone, this problem comes up when i try to turn on the screen the next time. I press the power button and the screen does not turn on. I try the home button and it does not work too. I try charging the phone to see if the screen turns on but it does not and the led light does not indicate that the phone is charging. When the phone is charging and this problem shows up, i try unplugging the phone and the led light indicating that the phone is charging does not turn off. The only thing i can do is press and hold the power button and let the phone restart. This problem happens ocasionally but today, it happend 3 times within 2 hours. Anyone knows how to solve this or has this problem too?