Computer shutdown when AFK?

[im4eversmart]

Im running on windows 7 professional, i5 cpu, 8gb ram

My computer is fine when i am using it, but when i leave it for long periods time such that it goes into sleep, it automatically shuts down, and when i turn it on again it says my computer did not shut downproperly and i get to chose whether to normal start up or go into safe mode

What can be causing this problem?

 

[Rain08]

Are you sure that its shutdown not sleep?? Because windows 7 can sleep your computer after X amount of time like 20 minutes.