Macbook Pro would not recognize HD
MBP randomly crashed one day and then would not boot up past "folder with a question mark" icon. Bought a new HD from newegg and replaced the old one, but the %#*@ thing still would not work - Disc utility showed no hard drives present (over SATA at least). BOTH hard drives booted/recognized fine when I used an external usb enclosure.
Finally figured out that it may be the hard drive + IR cable itself. Bought one from ifixit (pretty cheap), it arrived practically overnight. Removal of old cable and installation of new one took about 20 minutes. Problem went away IMMEDIATELY. !&&* yes.
don't ever pay to have apple fix your mpb if it's out of warranty.