desktop appears, then screen goes blank and this cycle never stops

[Rondo]

I activated W10 and played with it for a while and everything seemed ok - I restarted the computer a few days later and the problem above began - the screen goes blank for a split second right after the taskbar items appear and then the desktop appears again - and this goes on and on - I can't access any application

 

[Martinclift]

I upgraded last night (12th Aug) and the same has happened to me.
This upgrade was from 8.1.

As it continues on this 'on off' cycle the machine starts to over heat and the fan works overtime to keep it cool!