We are slowly upgrading our clients from 2012 to 2014R2 SP1 Hot Patch 1. A few of our office managers need access to multiple calendars at once (at least around 20). This worked in the previous version with the Multi-User Columns option. Now a couple of our users are reporting that the client will suddenly go gray. They have to kill the application and restart. It only happens when they are in the calendar. Has anyone heard of this issue in 2014?