Q: Why does safari return a blank screen for support.apple.com links?

No matter the source of the link (other discussion sites, Apple Support, etc.), when I click on a link of the form https://support.apple.com/en-us/HT204416, Safari returns a blank page. Firefox exhibits the same behavior!

I've disabled the only two extensions in Safari (SafariRestore and DuckDuckGo), restarted the laptop, even tried using an admin-only account that doesn't have the years of use that my normal login account (standard user). But again, since this happens in a rarely-used but latest version of Firefox I don't see what the two Web browsers have in common other than login user and OS.

Note that I don't have this problem on the forums.apple.com site or other third party question/answer sites.

Any ideas or others with the same issue?

I'm on a:

Hardware Overview:

  Model Name: MacBook Pro

  Model Identifier: MacBookPro10,1

  Processor Name: Intel Core i7

  Processor Speed: 2.3 GHz

  Number of Processors: 1

  Total Number of Cores: 4

  L2 Cache (per Core): 256 KB

  L3 Cache: 6 MB

  Memory: 16 GB

System Software Overview:

  System Version: OS X 10.10.5 (14F27)

  Kernel Version: Darwin 14.5.0

  Boot Volume: XXXXXXX

  Boot Mode: Normal

  Computer Name: XXXXXXX

  User Name: XXXXXXX

  Secure Virtual Memory: Enabled

  Time since boot: 7:26