Long story short, after upgrading to Yosemite I cannot put my computer to sleep and wake it up properly with 2 monitors on and connected. I have spent hours on the phone, and been to the Apple Store twice trying to resolve this issue. They replaced the: 5400 HD, logic board, and SSD in my computer trying to resolve this and when I brought it home for the 2nd time last night I was still having the same issues. When I put the computer to sleep and wake it up the computer is inoperable. I cannot click anything, the computer is frozen. Work around: The only way I can make my mini and sleep work is to: Step 1) Turn 2nd monitor on, 2) Put mini to sleep, 3) Wake mini up, 4) Turn 2nd monitor on. Apple will be getting a call later so I can report this bug directly.