When I connect a bare SATA drive to my 2010 Mac Pro 5,1 via a Seagate GoFlex FW800 adapter, then it works fine. But when I connect two of them simultaneously, then they both eject and are nowhere to be found in Disk Utility. After that, I can't make any of them mount individually again (or even show up in Disk Utility) until after I reboot. The Seagate GoFlex FW800 adapters also have a USB 2.0 port, and if I connect one drive via FW800, and the other via USB 2.0, then they both mount simultaneously. But if I use the FW800 ports on both adapters, then they both eject and disappear. Does anyone know what's going on and how to solve this?