I have a 1TB LaCie external and I want to backup my MacBook Pro, but it isn't being recognized. I plug it into an iMac, and it is recognized and I can view everything on it, but it doesn't even show up on my Pro. It was showing up the other day, but now I can't even see it under Disk Utility. On my iMac, I checked the HD under Disk Utility and there is nothing wrong with it. The Pro is connected to the charger and is at 100%, but could it still be an issue with power? I also tried relaunching Finder, but nothing changed. I closed down most everything I have open but to no avail. I'm kind of at a loss for what to do, any help would be appreciated. The computer is old and runs very slow, I don't want to lose anything.