Hi @Flood and Flood's wife , thank you so very much for responding. Dreadful would be an understatement, really. Yes, I have done a quick check on installed apps incompatible with the Kaspersky product and I don’t have any of those on my Mac. My MacOS version is the 11.0 Big Sur and it meets all Kaspersky system requirements. I’m incredibly frustrated, I can only hope the technical support gets back to me in time.