Thanks for that info. I've followed all the advice about Tablet and so forth, and in fact it has never been turned off. I've also got the Tablet PC Input Service running.
An interesting phenomenon has arisen. I use Opera, and have just updated to the latest version 11.50. At the same time I've reinstated my Snipping Tool.
Now, when I start Opera, I get a (presumably) system message about the Snipping Tool shortcut being moved and so forth.
I attach a snapshot of the relevant message taken, as it happens, with the Taskbar Snipping Tool!
I should add that this only happens so far when starting Opera, and I've got quite a lot of Microsoft and other applications being started on here every day.