Well, I wrote to the folks at QRZ and they replied with “Your QRZ page has been restored from a backup copy. Our server recently had a database upgrade and a few bios were not copied properly. We apologize for the inconvenience and hope that everything is OK now.”
In fact, the page had not been restored and it took another email to get it sorted out. I still don’t really understand why a “copy” exercise would fail at the beginning of a URL but the important thing is that the page is restored now and I can get on with editing it.
Thanks again to the back room boys at QRZ.