OK, try tapping the F8 key when you first turn the computer on, it should give you a boot menu, scroll up to "boot in safe mode" select it, hit enter and see if it will go there. If it boots into safe mode, run a virus scan and a registry cleaner, when done, reboot to normal mode, it should work. Oh, if the OS won't boot on the old drive, it's not gonna boot on the new drive.