Diceman,
I had the same exact problem. I had once properly installed the Symantec authentication client plug-in (I believe people refer to it as VIP or PKI client), and had it working on my Safari browser. I accidentally removed the tblive-4.plugin from my Internet Plug-Ins folder in my Library files. From then on, I could never get the darn thing to reinstall on Safari. Same on Chrome. But I downloaded Firefox, and that seemed to work.
I still wanted it to work on Safari (my default browser). I felt like something must be being cached in the background, but I wasn't sure. Any case a few hours of research (where I first stumbled into your link) and some amount of experimenting later, I finally stumbled into an internal corporate site that had a troubleshooting page, and at the bottom was a file for Mac Symantec plugin uninstaller (It was labeled: symantec-auth-client-plugin-uninstall.dmg). I closed all my browsers, ran that, then I logged back into our secure site, and this time instead of getting the errors, it properly registered my computer. Now, everything is working again.
I was so happy, I went through my history to find this link, logged in a new Apple account so I could write you back and share the information. I couldn't find the uninstaller anywhere on the Internet to download (otherwise I would've linked it for you), but I would suggest you reach out to your internal IT department and ask for this Symantec client plugin uninstaller.
I know that answer might not get you all the way there, but hopefully it gives you what solution you're looking for now (assuming we're facing the same root cause issue).
Best of luck! By the way, I went to school with a guy who was the president of our fraternity (DTD) in Michigan, I know it's common, but his nickname was "Diceman". You didn't go to school at GMI in Michigan by chance, did ya?
-Ed