I have a 21 inch MAC desktop computer I bought from Best Buy a couple gears ago, after my three long time Windows Computers crashed. I have to admit the conversion to Apple was a real pain in the ass. But now I can get the MAC to do pretty much every thing I need it to do. Last night when I tried to turn the computer ON, the USB lights, of the several One and Two TB plug in hard drives ran (so I knew the computer had power) but nothing else appeared to work. Just a blank screen. I tried a number of times, switching the power ON and Off but the computer appeared to remain dead. This got me to thinking, "What the hell do I do now?" You don't realize just HOW MUCH very important stuff you have stored in the Computer, until it looks like you may have lost it. When I tried to turn the computer ON, a couple hours ago, it started up normally. ??? Now I'm afraid to turn it OFF again. One of the 2TB USB drives I bought was intended for the "Time Machine" backup, but some time back I stopped the automatic Time Machine backup because I needed the space on the drive. So, if I allow the automatic Time Machine backup to automatically do it's thing, and if this computer does crash and I buy a new one, how far does this Time Machine back up drive go to restoring the new computer to the old computer settings? The "Time Machine" backup disk still has 400+ GB to go. .