Right then, I followed your suggestions but did not install an updated (Intel Graphics) driver as I was already up to date.
However, I did check your Blue Screen link and, as per Microsoft's recommendation increased the size of my swap file (actually, let Windows do its own thing, as even though there are concerns about the page file on an SSD it would take many years to 'wear out' the cells in an SSD for the average user [not that I'm in any way 'average', of course]).
Result: success! It generated the file just fine, thank goodness, now live on YouTube.
As an even more interesting aside, I also installed one of the MP4 'joiner' utilities you gave me a link to and ran that whilst the video was exporting with no ill effect (probably because 4.58 doesn't use all available CPU). The video was 'joined' with no side effects except that there was (obviously) no transition from one video to the next, just a hard cut. But this joining exercise completed before the VP video finished exporting.
The rendered video from VP is 390Mb
The 'joined' video (from two VP-generated videos) is 146Mb.
All were generated at 8192 bps, 128k audio and a fixed 25fps at 1080p HD quality.
So why the difference in size (but not perceived) quality? Well, the 'joiner' utility seems to have downgraded the bps setting from 8192, but even VP reports that the Bitrate in the final video is just 1425kbps (is this the same thing?) and the joiner says its joined video is 531kbps - both well down from 8192 but maybe I'm confusing apples with oranges.
The raw video footage imported into VP reports it is 24854kbps which seems quite high but I'm not sure how much control I have of that (generated by OBS).
The most important thing is the final quality seems just fine.
But clarification on what the bitrate is of my videos would be useful (in the export dialog box I've always set it to the YouTube recommended 8182 kbps).