The problem is that Cubase 8 freezes

Hello! I wonder what I should do for me to edit MIDI. I have Cubase 8.02 and OS X Yosemite 2.66GHz Intel Core 2 Duo Memory 8GB of 1333MHz DDR3
Graphics NVIDIA GeForce 9400 256 MB. The problem is that Cubase freezes so I have to force quit the program. Thanks in advance. Ronny …