TC providers get installed under Host->Host Settings->Authentication Services. I haven't had a chance to check the core scripts but check out this thread (http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/89/threadid/172747/scope/posts/Default.aspx) and check the sql procedure mentioned to ensure that it's correct. That might be the cause of your problem.

George Gildea wrote   I had the same issue. It occurred when upgrading from DotNetNuke 04.05.05 to 04.06.00 using the source package. Here is how I fixed it. Upgraded from 04.05.05 to 04.06.00. I accessed the website and received the following error: A critical error has occurred. Could not load the assembly 'DotNetNuke.Authentication.LiveID'. Make sure that it is compiled before accessing the page. Copied the following files from the 04.06.00 install package (DotNetNuke_04.06.00_Source\Website\Install\Package) to the {website}\Install\Package directory: LiveID_01.00.00_Install.zip OpenID_01.00.00_Install.zip Downloaded ActiveDirectory_01.00.00_Install.zip and added it to the {website}\Install\Package directory. Via the browser, ran "http://{website}/Install/Install.aspx?mode=InstallResources" with the following results:             Install Resources Status Report             00:00:00.031 - Installing Package File ActiveDirectory_01.00.00_Install: Success             00:00:00.375 - Installing Package File LiveID_01.00.00_Install: Success             00:00:00.625 - Installing Package File OpenID_01.00.00_Install: Success             Installation Complete Accessed the website and got the following error: Parser Error Message: Could not load file or assembly 'DotNetNuke.Authentication.ActiveDirectory' or one of its dependencies. The system cannot find the file specified. (E:\Websites\DotNetNuke\Aqua-Marine\web.config line 68) Copied the following files from the {website}\bin\Providers directory to the {website}\bin directory:             DotNetNuke.Authentication.ActiveDirectory.dll             DotNetNuke.Authentication.LiveID.dll             DotNetNuke.Authentication.OpenID.dll             Janrain.OpenId.dll  Logged into the website.  Under host setting, installed ActiveDirectory_01.00.00_Install.zip.  Upgraded from DotNetNuke 04.06.00 to 04.06.02 using the source package. Upgraded from DotNetNuke 04.06.02 to 04.07.00 using the source package. Upgraded from DotNetNuke 04.07.00 to 04.08.00 using the source package. Everything seems to be working OK. Hope this helps.

Indeed that did help.

I run a server with about 8 different DNN websites (not portals but sites). So I'm adding another one the other day, and I'm doing a fresh install to 4.8.4. Fresh installs are always a pleasure. But as I'm copying connection strings etc. from a good install(4.5.5) I paste into my new release.config rename etc. typical day at the office. So much so I get up to get a soda. smoke a cig... and fire off the install page...

  oops. forgot to change the conection info in web.config for the NEW site, and the script updates the WRONG db. So I was stuck with the other site at version 4.5.5 assembly with a 4.8.4 database... doh! This caused the default(pre-LiveID/OpenID) login to fault, so no login. No choice but to bring that site up to 4.8.4

Possibly the most botched upgrade I've had to do but finally got the db and assembly versions straight and working. had to go from 4.5.5 to 4.6.2 don't know why but straight to 4.8.4 wouldn't go(as i've noticed about 50% of the time) But I still had no way to login. Throwing the LiveID/OpenID error. 

Thanks for posting a full solution that worked for you, it was refreshingly logical after todays insanity. And it worked lie a champ. Now I just have to go through and clean up "Copy of folder(12)" and the dozen or so web.configxx(x)...

cheers

-mk