Had been having intermittent problems with both my Passport and Passport Ultra drives not mounting or if they mount, then unexpectedly ejecting themselves.
Only going to discuss the Ultra here, because it looks like I might be making some progress with the Passport. [BTW have registered both, but only the Ultra seems attached to my account.]
I have changed cables, tried in multiple machine configurations—Mac and PC, Mavericks and Yosemite, Windows 7 & 8.
With the Ultra, I can now on a couple of machines get it to mount; and not eject on its own accord. Using the Drive Utilities, I can perform both a Smart check and Quick check, Complete Drive Test cancels itself after 5–10 minutes?? Have tried a number of times to perform this check. I have followed all steps in ID 505—so no changes there.
I did try to install the Firmware update, but doing multiple scans always returns the result “No drive found”—I managed to do this on my Passport, and now, fingers crossed, it seems stable.