I posted this in Apple support but haven't seen a response, so I wonder if this problem is only my own. Here's the story... I just got the latest & greatest iMac 27" i7 2TB with SSD (and 12GB ram) a few days after they launched (had it a bit more than a month now). Wow! It's great. To it, I've attached some USB hardware as well as a WD 4TB firewire 800 drive: Western Digital My Book Studio Edition II. Things seem to work well most of the time, but I've noticed more than once that attached hardware gets dropped. In particular, I've got a Parliant USB device (part of the Phone Valet package which makes the Mac a great voice mail machine) that is sometimes there and sometimes missing. It's hooked directly to the back of the iMac (not a hub), and I've tried switching which USB port it's plugged into on the Mac. This device worked fine for years hooked to a PowerMac G4. But now, it is often in the USB (attached devices) list, but sometimes it's gone. When it's gone, my business voice mail system is also offline... NO GOOD. I have to unplug and then plug it back in, or sometimes reboot. Similarly, I've got a USB scanner that is often in the list of USB devices but sometimes gone. Unplug and replug and it's there again. The WD is hooked to the firewire 800 port. I use it mostly for iTunes video media. It will simply disappear from time to time, and I don't get any kind of (the usual) "warning" message about a disconnect without ejecting. It's just there and then it's gone. This is my second WD drive; I returned the first one for this same reason, assuming I had a bad drive. A second one doing the same thing makes me think it might be the iMac instead. I used Disk Utility on both WD drives. I even tried Disk Warrior on the first one that I returned. Neither found any fault with the WD format or hardware. Like the PhoneValet USB attachment, the WD will come back by unplugging the firewire, waiting a few seconds and then plugging it back in. Or I can reboot the Mac. But in both cases, what I want is for them to always be "on", not (seemingly) randomly there and then not there. I starting to suspect a bug in the hardware ports on the iMac since both a firewire (2 in a row actually) and at least 2 USB devices are exhibiting these disappearing sequences. I've got the iMac hooked to a good battery backup/surge suppressor, so I'm pretty confident the problem is not related to spikes/brownout/blackouts. Everything else works great and has since the day I received it. I work many hours each day on the Mac and all seems fine, except for these attached device drops. Anyone have any suggestions? Anyone got the same kinds of problems? Is this a "take it to the Apple store issue?" And, if so, I'm convinced that I can't demonstrate the problem to them as I can't seem to make hardware disappear on demand. Thanks for any input/suggestions!