I installed a brand new 500 GB Western Digital Scorpio Blue hard drive back in April, been running Lion 10.7.3 since without any problems. Until tomorrow when I go to start up my computer and all it does is go to the Apple logo and the loading screen. Putting in my old hard drive the computer works fine, and when I run Disk Utility by booting it through the OS X Install Disk I can verify/repair disks without any problem. As far as I can tell all my data is still on there (still says some files on System Profile and still recognizes my hard drive name and OS) but I can't get it to boot. Western Digital says they'll cover it under warranty, but I'd really rather just fix this rather than go through the whole process of shipping it out and waiting to get a new one then loading all my info over. Can anyone think of a way to troubleshoot this? Or at least what may have gone wrong? Haven't downloaded anything shady lately at all. Thanks.