I'll save the details for now, but during the middle of the download of 10.6.8 last night I was having intermittent internet issues, and it was late so I decided to power down my Mac and finish up in the morning. I've done this mid download, and resumed later without a hitch many times before. NOTE: I did not power down during the install. However once it finished installing this morning, it asked me to restart and I did, but now it hangs at the grey install screen with the spinning cog wheel. It gets a little less than a quarter of the way through and then just shuts off. Any ideas on how I can fix this? Because now my Mac won't boot up at all. This is an early 2011 MacBook Pro if that helps. I also have access to an older 2007 MacBook Pro if needed. Any ideas?