This has been mentioned several times on these forums, and especially on the Apple forums as well (https://discussions.apple.com/thread/4174723?start=0&tstart=0). I have a Fantom Green Drive USB 3.0 directly connected to my new 27" iMac. I am using it as a TM drive and also as a source for a CCC backup in a second partition. Whenever the iMac goes to sleep the drive is immediately disconnected and when I wake the machine I get the "did not eject drive before disconnecting". I had assumed this was due to the brand of drive I was using, and pretty much decided to just keep the Mac from sleeping ever (although the display does sleep). However, after seeing the above thread, it appears that: 1. This occurs with a whole lot of drives 2. It occurred with drives that worked fine before the OS upgrade to ML 3. Nobody seems to have any specific solutions except for keeping your computer awake 24/7. Given all of the above, this sounds like a bug associated with ML. I'm wondering if anyone else using Green Drives has this problem, and I'm also wondering if I am missing something in the settings. I have tried with "Put hard disks to sleep when possible" both checked and unchecked with no difference. I have checked "wake for network access", "allow power button to put the computer to sleep" and " start up automatically after a power failure" as I can't see that these would have any effect. The drive works perfectly as long as the computer is awake; if I put it to sleep it immediately disconnects. I've sent a ticket to the company to see what they say, but I'm wondering if others have found a solution to this.