Has anyone ever had this problem before ? 

Stereo just randomly turns itself off & on when it pleases, it's not all the time like  Saying that it sounds like the missus  So it could turn off after being on for just ten minutes or being on for two hours with it being unable to be turned back on no matter what we try, be it by button or ignition keys, then it might be half hour of being on and it turns off, maybe for 5 minutes at the most it kinda plays dead  Then it will work continuously and faultlessly for months, then it has a fit  it strangely comes back to life on its own and shiit's us up 

Fiesta 2010 with a Sony unit.

Added the Emoji's to make my thread less boring  

i would proffer a bad earth

1 minute ago, Jimpster said:

i would proffer a bad earth

Could be a start but heck where do I even start to look for an 🌎

13 hours ago, Ian Lanc said:

... where do I even start to look for an 🌎

One way to test the theory, would be to make a new ground connection (the "-" side of the circuit). You'll need to connect the metal body of the Audio unit to the metal body of the car (could be a bit of a faff, mind. Just ensure that you've a good solid connection and test it, if you can.), then see if the problem persists. If it's not the ground connection, then (again, in theory) it has to be the 'live', or the power feed (the "+" side of the circuit), if you will.

4 hours ago, Rob101 said:

One way to test the theory

Blimey I reckon I'll just let the stereo act up like a woman!
It's been on for 3 hours today and worked fine...Very odd.

18 hours ago, Jimpster said:

i would proffer a bad earth

I know, the 'just stop oil' nutters are all over that 😂

Might be worth taking the head unit out and making sure the wiring harness is nice and tight.

Mine had an issue where the speakers in passenger door would jst decide to go on holiday when the fealt like it.🙄

May be worth as loose connections come and go as the car moves about ?