Licensing/Login issues on Win10 x64

(Below is the text of an email I sent to Support; I wanted to see if the community had any suggestions as well!)

Hello Unity Support,

I’ve recently begun using Unity 2017.1.0.p4 on Windows 10. I possess a Unity developer login and have been using the editor successfully with a Personal license for the last few days.

Today, Unity is presenting me with this screen upon startup:

(Yesterday I installed some updates [incl. BIOS update] from my computer’s manufacturer; it’s possible that caused this machine to appear as a ‘new’ one to Unity).

The problem with all this is that the Sign In button at the top isn’t functioning, and the Re-Activate button isn’t enabled until I can sign in!

Here’s what I get if I try to ‘Sign In’. A blank page with no controls!

Clicking ‘My Account’ does take me to my Unity ID’s Web profile, so apparently some part of the usual functionality is working, but I can’t re-activate my license and this is blocking me from using the software at all.

Steps I’ve taken so far:

  • Uninstall, redownload, and reinstall Unity

  • Log in to my Unity ID via the Web interface to ensure credentials are correct

  • Restart computer and retry

  • Delete ‘Unity’ folder under /Users//AppData/LocalLow and retry.

Please send any advice you may have for resolving this issue; thank you!

Really loving your software (when I can access it),
-Connor Shaughnessy

(For some reason IMGUR links didn’t work above; images are here.)