I have an iMac running Yosemite and Lightroom CC. Since updating to the latest version, Lightroom will periodically crash (every5 to 10 mins) and cause the Mac to restart. I have turned off the graphics accelerator, deleted the SLCache and SLStores and yet it still happens. The previous version of Lightroom worked very reliably, this latest one is unusable. Please help me either fix it or tell me how to go back to version 5.