The User Profile Service service failed the logon. User Profile cannot be loaded

Many thanks, Einstein
Unfortunately this is way above my competence level, if what you say applies.
I think the instructions refer to Windows Server and do not apply to my Vista OS. I have looked for the ntdsutil.exe, without avail.
I can only access the system via the command prompt in 'System Recovery Options' on the Vista installation disk.
I was hoping that I could reconstruct the registry in some way to bypass the log-in screen, or perhaps create a temporary administrator profile.

You can also try the below solution to fix this issue:

Just right click on my Computer > Properties > Advanced system settings > Advanced tab > Under User Profiles, click Settings > In the User Profiles dialog box, select the profile that you want to delete > click Delete > Apply/OK.

Next open regedit and navigate to the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList

Right-click the SID that you want to remove, and then click Delete. Log on to the computer and create a new profile. Alternatively, you can simply download and use this Fix It 50446 from Microsoft given on KB947215, here.