Yay! Three more chkdsks later (the last from the command prompt of Macrium Reflect rescue disk being the only one to actually finish (and repair the MFT)) and the clone process finally worked and the...

OK, booted from the excellent Bitdefender Rescue CD (on USB) and logged in from Firefox on that.
Bitdefender showed 12 I/O errors before the CHKDSK scan mentioned in my previous post and still one...

Many thanks axe0. The difficulty I have is that the system is only up for 11 minutes maximum which doesn't always allow time for these scans to complete. I'll post the HDscan results as text, below,...

(Frustrating - wrote another post which got wiped when I went to add an image)
Anyway, this shows MsMpEng using a lot of CPU shortly before the PC froze. Unusually this time the disk blue line...

Well, I don't know what's happening now. First time I ran dm_log since lasty post it said something like system cannot find path to dump file. Having selected small dump I saw the path should be...

Hopefully, the Resource Monitor photo is now attached. On the right the second graph down shows the disk maxing out in the blue line. This happens whenever the problem is occurring. Now that just...

Thanks axe0. Yes, that's the BSOD I'm getting, except it just sits there on 0%. Sometimes it restarts itself without having progressed but, when it does, there's no boot device and a power off/on is...

Thanks for all your replies. Apologies but perhaps BSOD is not exactly what I'm seeing. As described, the system locks up/freezes at EXACTLY the same time after start-up each time, without fail (so...

BSOD/freeze after exactly 11min 15sec uptime every time.

This has been going on for some time while I've been trialing and erroring. Computer locks up exactly 11m 15s after power on (BIOS set to...