Safari certificate problem
I'm having a problem with Safari 10.0.1 on macOS 10.12.1
When I try to go to Walmart.com (no judgement please) all the images on the page fail to load properly. The Develop menu shows errors such as "[Error] Failed to load resource: The certificate for this server is invalid. You might be connecting to a server that is pretending to be “a14.wal.co” which could put your confidential information at risk." The page load fine with Firefox, but Opera fails like Safari. Safari on my other Macs with the same versions loads just fine. The Guest user on my Mac works fine. Obviously there is some issue with my user id on my Mac.
I have cleared the cookies & caches, looked at my Keychain, deleted cached files from my ~/Library and everything else I could think of. I even tried to reinstall the OS via Internet recovery (which failed because 10.12.1 is newer than 10.12.0). (For some reason I do not have a Recovery partition on my 1 TB Fusion drive.)
The only solution I can think of that I haven't tried is to wipe my drive and reinstall everything from scratch, which I really don't want to do. Any suggestions as to the cause and a simple solution?
Thanks, Dick
iMac with Retina 5K display, macOS Sierra (10.12.1)