I too am having this exact same problem. Nothing seems to be working. I am simply trying to import tiff files on my internal drive that are not yet in my catalog. I have also tried syncing a folder where the new files reside... still get same problem.
Macpro 2009. Mavericks OS 10.9.4
Lightroom 5.6
Import size doesn't matter. Not a single file will import.
Permissions are fine. It's an internal hard drive. Tried other hard drives, they all have the same problem.
Will try running safe mode....
