I found a bug in Lightroom 5. When shooting tethered, and naming the files, if a colon was used in the file name, the program would cease to function, and lock up during tethered import. After a heartbreaking day of trying to fight through a volume shoot day, we were able to find this fault once we returned to our studio. So, lesson learned, no colons in the name. Like "Barrett Group 4:30 PM". Big bad news for Lightroom.