I have Lightroom set up so that my Library resides on an external drive and I import using "reference files in existing location." The images are on the same drive (but in a different folder) as the Lightroom Library. All works fine for a couple of weeks, then out of the blue one day, I'll launch Lightroom (with the external drive plugged in) and there will be no images in my Library; all my Shoots/Collections/etc. will be gone -- it's like it's the first time I'm launching Lightroom. This has now happened to me three times, and it gets frustrating to have to reimport all the images.
What's even stranger is that the Library file still exists on the external hard drive: I can see it there, but I can't import it into Lightroom. And even stranger than that is this: if I just launch Lightroom, no dice. But if, instead of launching Lightroom, I double-click the Library icon in the Finder, it will launch Lightroom and voila, the Library is rebuilt. BUT (1) it launches 2 Lightroom windows; one properly displaying my Library, and another displaying nothing. And (2) if I close the "blank" Lightroom window, it closes the whole application, including the window that's working properly. And (3) if I quit Lightroom and re-launch it, I'm back in the same situation; no Library. So, each time I want to use Lightroom after this problem arises, I either have to (1) reimport all the pics into the Library or (2) do what I just described in terms of double-clicking the Library icon in the finder.
Thoughts, help or advice are appreciated.