How about reinstalling LR 5.3? Download here
I can't help feeling that if it was a Lightroom issue there would be a lot of other people reporting it. I can't find anyone else with Google.
Yea, I don't know what the deal is. I did a complete reformat of my hard drive and reinstalled OSX and DIDN'T do a Time Machine restore, I started fresh. The first thing I did was install software updates, then Lightroom. It worked!...until I started to reinstall other programs and putting some documents and stuff back in place. I then went to LR and to test it that it was still working and it wasn't. I hate to say this but I'm just going to give up. I can have LR work perfectly if I just keep the LR Catalog on my external HD, which is portable. I figure maybe its a sign. Its not like I would be able to keep thousands of RAW files on a small 256gb SSD in my MBP anyways.