Today I found that I can't access help on any system tool when I click <Tool Help> button. It says (see attachment):
Can’t reach this page
Make sure the web address //ieframe.dll/dnserrordiagoff.htm# is correct
Search for this site on Bing
Refresh the page
I afraid it is Windows 10 October update in action.
Anybody, who knows how to fix this, please! Last thing I want is profile re-build.