Why does my HP laptop boot up with a blank screen and hard drive light on?

I have a HP Pavilion dv6408nr laptop that when I either shut down or restart, it will then only show a blank (black but still illuminated) display with the hard drive light lit up stagnantly. I then am left with no other option but to manually press the power on, wait a minute, and then reboot. It then always boots up with no problem; no Windows System Recovery prompt or safe choice available. It acts like nothing has happened. How can I fix this? Granted, I did recently added more memory and a new hard drive? I'm betting those are the problems? I mean, other than that, my computer runs fine, no error messages, lock ups, or anything.