Hi Andrew, first I want to say thanks for answering, again, and thanks for giving your advice so freely, literally! You first helped me learn about colour management about 8 years ago on DPP and here you are still helping after all these years...
I ran PFA as you suggested and it found 15 Hasselblad profiles that it thought were wrong, and partly fixed them (although I've had no problems running H's Phocus) but nothing related to Eye One. There were 155 profiles in total. I also created another account but could not calibrate in that either. I am using the latest version of the software, downloaded today and reinstalled yet again. Also no joy with EyeOne diagnostics.
It crossed my mind to revert to 10.5.4, which I still have as a download, but there I think there have been so many patches since then and I'm not familiar enough with macs yet to try that. It might also mess up other programs that are working just fine.