Mac Mini and display issue

Last fall I bought the new Mac Mini 3 ghz i7 with Intel Iris, OS 10.10.4. I’ve had troubles with the display and sleep mode from the start, the display sometimes looks like the attached picture and the computer won’t go in sleep mode when Cubase 7 is open. Anyone know how to fix these problems?



This kind of view is very often because of cable issue (or some cross-cable, for example like from Thunderbolt to DVI). Please, check this, first.

It’s not a good idea to switch your computer to the sleep mode, when Cubase is running. After this, some initialization process could missing for Cubase, and it could cause some issues.