The problem seems to be an interaction between Windows 10 and Outlook (in my case Outlook 2010). A hyperlink in Outlook causes Internet Explorer 11 to open and display the message. To make sure it was not IE at fault, I pasted the same hyperlink firs to Edge, then to Google Chrome, but got the same result. So, I conclude that Outlook is at fault. I have read suggestions as a result of Google searches that other people have similar, but not the same problem when using Outlook 2010 or 2007 with Windows 10. Their problem appears to be that every time they click on an Outlook link it brings up a screen asking whether to use IE, Edge or Google Chrome - which they find annoying. There some suggestions on how to fix this problem, but not the "Hmm we can't reach that page" error.
Any suggestions please?