Guys I had same issues you describe back in Dec off last year is when it started. Mine started out as exit to desktop when I click on fly in a mission. Over a period of two month it progress to black screen, then to computer shut down and restart, too complete shut down, and I had to push the power button too restart my computer. That went on for another month or so. I tested every thing in my computer, even to the point on complete tear down and putting it back to gather, having too reset my BIOS just to start my computer. Took it to computer repair with no luck. Finally after reading many post on the internet with simullur problem, and many suggesting that the power supply may be failing, even though my voltages at main connector were good and showed the same in the BIO I broke down and purchased a new ( power supply ) installed it, and all is well now.
Something too think about