I've built a new sharepoint site page using the example I found here: http://blogs.msdn.com/b/kaevans/archive/2010/06/28/creating-a-sharepoint-site-page-with-code-behind-using-visual-studio-2010.aspx
The purpose of the page is to add a new user to the aspnet membership database that serves as the authentication provider for my sharepoint site, which uses forms based authentication.
I've slightly customized the asp createuser control.
The sharepoint site is forms based but the top level site is accessible anonymously, and I've created a subsite for members (hence the user registration page). The site page is in the top level site so that people can register.
If I'm already logged in and fill out the form, the user is successfully added to the membership store, however if I access the page anonymously and fill out the form, the user is successfully added to the membership database, but I can no longer navigate the website, I keep getting http 500 page cannot be displayed errors until I clear the browser cache and cookies.
I don't think it's a programming error but more likely something to do with site security and authentication