Thank you for all your responses. I only spotted them all this morning, as I had not received my normal e-mail notifications.
I downloaded Malwarebytes fron its own website, and did try Chameleon without success. Pausing the scan as soon as the objects appeared was not successful, as the computer froze before I could get a response.
I do have CCleaner, which I have set to run on startup.
I have also run the following installed software scans.
BT NetProtect Plus (McAfee)
PC Tools Performance Toolkit
All the above did not find anything.
However, I have now run Malwarebytes in Safe Mode, found eleven naughty objects, and removed them safely.
Many thanks for all your helpful suggestions
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