Computer crash on me at window loading

Well here is my problem, I have a desktop system i use for some gaming. One day i was playing civ 5 on my desktop and the computer froz on me so i had to reset my computer which i did and played civ 5 again and froz again so i just reset my computer again and do some web browsing and when to sleep leaving computer on which i do most of the time. Nextday i got on my computer and i press restart in start on my computer and i when to get something t eat and when i came back it had a error on the login screen. After i press the error screen which i dont remember what it was, my computer wont let me log in so i reset my computer and now whenever i start my computer in the middle of the window loading it crash then get .1sec of blue screen and reset.
I tried to login with the safe mode, i started with my laptop hard drive to see if hard drive was the problem and again it cant go in to window so what is the problem with my computer???