Screen goes blank after some time ( Dell inpiron N 5110 )

I have a dell inspiron N5110 and i am using window 8.1 pro. And my issue is when i use my laptop after certain period of time screen goes blank. And i when restart it doesnt work. And when i restore or repair the window then it works fine and still after some same issue occur. I tried re-installing the window multiple times but did found any solution. And when i ran the diagnostic test it gave the mentioned error: Hard drive error: error code : 2000-0146 Processer fan error : error code : 2000-0511 And for the hard drive i ran the the chkdsk in command prompt and dis nit found any problem. Please guide me on this. Thanks in advance.