Computer wont load OS

When I turn it on, it shows the bios screen then goes to grub boot loader, I run an OS and then it stops. In windows, it stops before it reaches the log in screen, I also have manjaro linux installed on a separate partition and that also never gets to the login screen, it just stops halfway and displays "_" at the top right. It has a 1tb seagate drive, and I have just cleaned and rebuilt the pc (It had this problem before I took it apart)

What should I do?

Have you got another HDD to try it with? Could be a HDD fault.

Sounds like a dead hard driveĀ 

I only have an external usb hdd, will that work?

Also, the screen does show the windows 7 pulsing icon thing as it starts up so the hard drive must be working for that to show p