Hi everyone. I've got a serious problem and was hoping for some help. I've got an '09 iMac that has been great. It is our lone family/home computer and has thousands of family pics, important docs and lots of music. All OS software has been religiously updated and the computer itself has been treated with kid gloves since purchasing it new several years ago. Until now it has worked perfectly. Today I DL OSX Maverick and afterward, as it was installing, I got an error message that said the HD was corrupted and Maverick couldn't be installed. It then restarted and is now saying it's installing OSX. Does that mean it's writing over my previous operating system, as in a new install like when we first purchased the computer? Has the computer "crashed" to the point that I'm about to lose EVERYTHING? I'd like to turn the doggone machine off to stop the install but I'm afraid that will cause even more irreparable damage. Please help.