Since I have upgraded to LR 5.5 in the last 2 weeks, I am continually getting "Adobe Photoshop Lightroom 64-bit has stopped working" and closes. I have only experienced this issue since the latest upgrade from the Adobe Creative Cloud. Windows 8.1 64bit, 16gb of ram. Happens when selecting a number of files, either to delete or work on in the Develop module. I also use Nik plugins, but was not using them at the time of all these issues.