I updated to LR 5.5 and later restarted my computer. I didn't use the program for a few days and then when I did, it wanted to backup the catalog. I agreed and closed the program. The next time I opened it, it asked me for my region, saying it was required. When I answered, I got an error message saying it has encountered an error reading the preview cache and needs to quit. It fails to fix the error and gives the same message over and over. I can't use the program at all. Customer service has apparently been discontinued and I'm really at the end of my rope with this whole company. I don't think I've ever had a mass-release program with so many problems.