Hey I recently replaced my HD in my girlfriends MBP(15-inch) due to the last one going haywire due to the laptop falling off the bed and hitting pretty hard on the ground. I installed the HD no problem but when I startup it just goes to the Apple logo and nothing happens, ive tried holding down C to make it boot from the CD/DVD Rom first and nothing. Also I forgot what command I used but I finally got the option to show up to Install Mac OS X but when I click on it the same thing happens, it just goes to the apple logo and nothing. Any help would be much appreciated! THANKS TO ALL IN ADVANCE! Edit: Holding down Option during startup allows the option to install MAC OS X DVD but like I said clicking it just returns me to the white screen with the gray apple logo and nothing happens.