laptop appear black screen

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everytime when i power on my laptop, and after half an hour or an hour, the screen will change to black screen...

when i activate stand by mode and power on it, the screen is become fine again

anyone know why this happen?

 

[robertconley619]

Sometimes on my dad's laptop, it would do this and usually because the laptop was overheating. idk, but that might be the culprit