Thanks you again for your replies, especially to Carolyn, who hit the nail on the head. The screenshot in her link matched exactly the malware running on this computer, and the date of the bleeping computer post, 27 March 2011, could not be more current.
Thank you also to Marsmimar, but for benefit of other users, your link was to an older post, and does not refer to the exploit doing the rounds right now.
And for the benefit of anyone else who likes to remove a drive from a problem computer and scan it from a clean computer, this exploit is NOT picked up by Malwarebytes, EXCEPT when it is running on the system drive. To clarify, here is the result of the Malwarebytes scan of the drive attached as a slave on my computer.
But here is the result of a Malwarebytes scan run with the drive running as the system drive in its own box.
And for anyone who is interested in these things, if you compare the screenshot below with the one in Carolyn's link, you will notice that the file names have changed, and they have added another registry corruption - the disabling of taskmanager.
Finally thank you Golden for your post. I take your advice on board, but FYI, I think the infection was left over from last time, because I did not then scan the drive in its own box. That was an omission on my part.