I have a lenovo z460 laptop that comes with a 2G ram 1333. I added a 4G memory stick 1333, but since i only have a 32bit operating system i only got 2.9G out of 6G. So i've decided to upgrade to a 64Bit OS. So i removed the 4G stick first to avoid conflict then installed a 64bit OS. After installing the OS I installed the 4G stick to the laptop then at boot i was prompted a system repair. But it only leads me to a black screen after windows loading files. Tried starting normally but im stuck with the loading screen.