Hi Basj,
Thanks for your reply. I did eventually uninstall Start11 via the purge batch file I downloaded from the website (invoking uninstall from the apps list in Windows 11 settings did not actually uninstall the app). Then reboot, download installer again from the website, ran that, this time success. Rebooted again, and now things seem to be fine.
Maybe it was the original installer file? I downloaded that one from a link in the email confirming my purchase, from your reseller FastSpring. This time, I downloaded the installer file directly from a link in My Downloads in my account area. I notice that file is named Start11_Setup_sd.exe whereas the original one I downloaded previously via FastSpring is named Start11-fs-setup_sd.exe.
All a bit of a performance! In any case, it looks like it's now done, and I see the computer I've installed this purchase of Start11 on listed in the listing of activated installs in My Downloads - it was not there before.
/Neville.