A couple of months ago I decided I wanted a fresh machine. I have a mid 2012 Macbook Pro Retina 15'. I did the fresh install by holding CMD+r while rebooting. Deleted the partition and formatted a new partition as per directions on https://support.apple.com/kb/ph21973?locale=en_US&viewlocale=en_US All went smooth. After a while, I started to notice apps Reminders, Calendar, Excel, heck even the Settings would just hang. I would force quit and think nothing of it. But this has become a regular thing. So I reinstalled again. And again. And again. Same problem. This is my work machine. I need it to work. When apps like Excel hang on the Save dialog box and I have to reboot to get them working properly again, in a business setting this doesn't fly. First I thought it was iCloud account that is why Reminders and Calendars were hanging. But Excel and Numbers too. Sometimes Numbers wont even start. It would hang on the start. So frustrating. What is going on here?