Well I do not know if anyone else is having this issue but here goes. I was using 5.2.4 for ages and apart from one or 2 small issues it was working great I have since tried to upgrade to 05.04.03 (71) and the register token no longer works. Either in my skin or the default skin or via the login box it goes back to the home page.
This has been an issue since version 5.3.0
I decided to try a new approach so I setup a new site with a brand new install. first I tried 5.4.2 then 05.04.03 (71) both from new installs and the same issue has happened. Since they changed how user profiles work it has stopped working. So to make sure it was not my server I gave it to a colleague who uses DNN on his server and  he had the same issue. He tends to use the source code and change it for his needs but to help me he did an install direct from the install pack and the register did not work.
We are both using SQL expresss 2008. We both have ASP.NET 4 on our servers and we are long time DNN users. I rarely post on the forum as 90% of problems I fix myself. We are both operating on 2008 R2 Servers. and the sites worked fine in 5.2.4 of DNN it is only since 5.3.0 this has been an issue. I want to upgrade to use telerik as I have been using it on other modules and projects for ages but now its part of the core it gives me more flexibility on what I can do.
Sorry I forgot to mention that this is the community edition of DNN if that makes a difference. I have upgraded DNN Sites the same way for years without many issues and then this please can someone help. Any Solutions or Ideas Much Appreciated.

Thanks
Paul
http://www.manctech.co.uk/- Fresh install of dnn 4.5.2 and no one can register till this is fixed.

I can confirm a problem with this. I'm encountering a redirect loop when I click the registration link on my test portal; freshly upgraded from 4.9.5. to 5.4.3 All I can say is thank flipping christ I trusted my gut instinct and checked this forum one last time before I carried out the permanent live upgrade I've been preparing for all day... what a nghtmare situation this would have been! ... Update - I've figured out how to get around it. Go to Admin, Site Settings and set the registration page to "None Specified" instead of the new "User Profle" page that is applied during the update. This new profile system has not been thought out for upgraded sites. I'm preparing to go through all portals and manually reconfigure the profile/registration pages/settings anyway, so I'm glad you spotted this issue and posted. Hopefully there's nothing more serious to it. Rob

Your skin object looks like a third party one. Is that correct? Rob