I can confirm that this problem exists.
http://www.foodweek.com.au and http://www.fooddaily.co.nz - are the same build - eg.. I replicated the database and site from foodweek to build fooddaily.co.nz from a 4.5.1 build.
However, we had an earlier build running on the dev version of http://www.insideretailing.com.au and because the clients had already put content into the site, I decided not to use the 4.5.1 build but continue on with the existing site. It was upgraded to 4.5.3 and their is an issue which has been logged (John Mitchell informed me) which was something to do with the NavigateURL code.
This caused serious problems with registrations since the site is being heavily marketed and, as mentioned here by others, the registration page was completely blank. The login link didn't work either. I thought it was an FF issue, but it was in fact a DNN issue.
Fortunately, John was able to rectify it for me and thanks to his extensive knowledge on the workings of DNN, I've been able to solve this.
It's very frustrating, since I can't tell you in this instance, how many hours are lost in thinking initially I've done something wrong. I'm sure I'm not alone. But it's fixed and we can move on to finalising this project.
Nina Meiers
My Site - My Blogs - Goodies - 28 Free DNNSkins - Nina's Free Skins
Nina Meiers My Little Website
If it's on DNN, I fix, build, deploy, support,skin, host, design, consult, implement, integrate and done since 2003.
Who am I? Just a city chic, having a crack at organic berry farming.. and creating awesome websites.