I got a new Seagate FreeAgent Pro today to use as extra drive space now that I'm shooting in RAW...I have an existing WD MyBook Studio Edition that I have hooked up via FW800 for Time Machine backups. Once I plugged in the FreeAgent over FW400, my MyBook stopped responding and wouldn't power off even if I held the power down. I had to pull the power plug and let it sit for a few minutes. After I plugged it back in, it responded to my power on/off commands but OSX wouldn't recognize it. I check disk utility and it doesn't show up there at all. I've rebooted a couple times and it hasn't seemed to help...even when I unplug the FW400 drive from my computer directly, the FW800 drive still won't recognize.