I installed Lightroom 5.5 a month back. I had no other versions of Lightroom on my computer before that. I have Photoshop CS6 and Photoshop CC on my machine. I want to add Noise Ninja standalone as an External editor and have tried to edit preferences. I use Windows 8.1 on my desktop. Every time I click on Edit->Preferences, Lightroom stops working and exits. I read the forum and once removed the Preferences file and restarted. The problem still continues. I am unable to find a solution.