I was installing the photoshelter plugin and noticed my external hard drive was not displayed. I had to import the whole drive again. Now when I try to import from my cards I get the error that this version of LR cannot work with my camera files. It has been working with them for years so what's up?
It's a long shot, but if nothing more concrete is posted, as you had just installed Photoshelter, have you tried uninstalling it and seeing whether this makes a difference.