Safari hangs on sign-in to Apple websites
Newest Os Sierra on 2013 Mac Book Air hangs and will not allow anything to occur on sign-in to Apple website. Correct user name and password. It just stops and doesn't allow any more entry, Can not even delete anything to occur. Other computer and devices work fine. I can't think of any first aide things to do to work around this. Quitting Safari does no good. Restarting computer does no good either. Any other ideas? Otherwise everything is ok. I can get on the Apple Discussion Board bur can't sign in. As I said I have the right User Name and Password. Other web-sites work fine. This is limited to the Apple ID and Apple sign-ins. Ideas?
MacBook Air, macOS Sierra (10.12.4)