I replaced a hard drive on a Toshiba laptop that was running Windows 7 Home Premium 64 bit. When I try to install Windows it says it is loading files, then starting windows, then failed to start: \windows\system32\ntoskrnl.exe is missing or corrupt. I tried 3 different discs and got the same result. I cleaned the discs, burned a new disc, did a full format on the hard drive from another PC, tried an external DVD player (which wasn't recognized) and got the same result. How can I fix this?