Thanks Chuck. @ChuckPa
Well, I seem to be running and stable again … a good couple of hours now.
I moved the ‘pictures’ folder as you suggested, and all was well 'cept Plex didn’t like not being able to find it 
.
So then I removed my whole Photo’s library from Plex, put ‘pictures’ back’ and created a new photos library pointing to a single folder way down the nesting in the ‘pictures’ share. Still OK.
So then I added another photos library pointing at the whole of ‘pictures’ again. Took a while to finish rescanning, but running OK since.
You are obviously right about PMS scanning the @recently-snapshot files, but there is almost nothing in there now, so maybe thats why it’s OK. The only files are a desktop.ini and the attached .plexignore file which I thought would make Plex ignore the folder. Of course, it doesn’t have the .txt suffix, I added that to be able to upload it. It’s not an empty file. Does it need to be, I wonder? If not, it points to a fault, I think.
.plexignore.txt (102 Bytes)
It looks like I have a workaround for now, but I am very reluctant to move ‘pictures’ permanently.
You were suspicious of the nesting being a QTS problem. The folders’ structure was not set by QTS. ‘Pictures’ is a QTS Shared folder and the contents are accessed by various other bits of software running on my windows PCs, principally Lightroom which I use for my photographic work. That where the folder structure has come from; by my choice admittedly.
I mentioned the problem with the ‘Remote Access’ flag. That seems OK new, too.
Thanks for looking and your help. I’m OK for now, but do look forward to a proper fix. Happy to check a beta if you like.
regards, Ian
