I will carry out a full scandisk, just to be safe, the next time I re-start the computer ( I would do it now, but I've invested so much time in this over the past two or three days that I'm getting little else done! ).
The ThisIsMyFile idea just doesn't seem to be working, for whatever reason:
If I drag and drop the folder to the icon, the MoreThisIsMyFile window comes up and the only available option other than 'only info' and 'refresh' is 'Reboot & Delete without query ( no unlock )'.
If I either use Alt+F4 or click the cross in the top right-hand corner to come out of that window, it returns to the 'ThisIsMyFile 3.81 - Admin (wow64)' window. Apart from 'only info', there are three options: 'unlock', 'delete', 'reboot & delete'.
If I click on 'unlock', it returns to the 'MoreThisIsMyFile' window that I've just escaped from, still with only the option of 'Reboot & Delete without query ( no unlock )'. If I click 'delete', same thing. If I click 'reboot & delete', same thing. As stated previously, even if I do click on 'Reboot & Delete without query ( no unlock )' in the 'MoreThisIsMyFile' window, it doesn't work; it will reboot the computer, but the folder is still there and undeletable.
Also tried 'DropPermissions' - absolutely no effect.
Tried reducing User Account Control to minimum - this does appear to have made a difference, though not a helpful one: now, instead of telling me I need administrator permission, it's telling me I need my own permission - which is to say, it tells me 'You require permission from xxx to make changes to this folder', where I'm already logged on as xxx ( with, as far as I can tell, full administrator permissions and privileges, as should rightly be the case since I'm the only person using this computer ).
Any ideas how I can either give myself permission to delete a folder or else delete it by some other means?
I'm not too proud to beg ...