so i have a unibody macbook pro that came with a 250GB hard drive and 2GB memory. Went to OWC's website and bought a seagate 500GB 7200RPM hard drive and an OWC 4GB memory pack. Installed them. when i turned on the laptop i heard the chime and then got a folder with a question mark? do i have to do something after the install? could it be a defective hard drive? thanks.