Thank you for that. I searched on my iPad for answers.microsoft.com and got the same reply, that is Control + Alt + Delete ... Oh, just noticed it actually said Control + Shift + Esc and thinking back what I could have pressed was Control + Alt + Escape Anyway, all seems well now, but I'm wondering if there's a nasty little bug/trojan/bastard/whatever still lurking beneath the surface in my computer ready to pounce, or perhaps it's already pounced and done its dirty work. As you can tell I'm worryingly clueless about these things.
As for "If you can navigate your way to their folder you can zap the EXE file and set the likes of Malwarebytes at it ! Ermm, no, and may I quote (see above): As you can tell I'm worryingly clueless about these things.
Hmm. That has just sunk in. For no apparent reason the screen did go blank and then came back on as if I'd restarted my computer: that is what Alt + etc + etc is supposed to do after all, right? As I said above I'm not quite sure what I did exactly but I was happy at the time that everything seemed to work fine once more, should I be worried? Have I fucked up?