I have several firewire drives connected to my 27" i7 2.93 ghz 2010. One or more of them I find are unmounted, and I have to restart to see them again. I thought I had solved the problem by getting a powered firewire hub, and by unconnecting my older Drobo. After doing those two things, the drives had stayed mounted for a few weeks. But now it's starting to happen again. Not as often as before, but it's definitely recurring. I've had the iMac checked out several times at an authorized mac shop and they say everything's fine. It does happen when I get a crash or near crash sometimes. But it also has happened when everything's running just fine. Anyone have an idea what I might be able to look at to solve this? I got tech tool pro, but it doesn't seem to have a section for this particular issue. I also use Disk Warrior, and Disk Utility etc. thanks!!