On my Win 7 64 Pro computer I set my Import destination to a folder on a dedicated HD, but after working that way a couple of times (shutting down the computer and opening LR the next day for a new batch of photos), it spontaneously reverts to the original folder on the C: drive and, if I don't check it every time I do an import, I have to move all those files back to where they belong.
Why doesn't the default drive setting for Import stick permanently?
