For those facing the black screen issue after the upgrade, pls try this:
Organiser-System Settings-Power Saver Settings. Turn both options to OFF.
I suspect that when the screen goes black, the box has actually gone into power save mode. I tweaked it at 10pm today, and have not faced the issue for last 3 hours.
The above is only a suspicion, and for friends to try it and report to help others having this issue. Thank you.