I have an ASP.NET MVC 3 application with forms authentication. For some reason that I cannot see, the login redirect url is /Account/Login?ReturnUrl=%2fSecure%2fAction
/Account/Login?ReturnUrl=%2fSecure%2fAction
To fix this problem, which still exist in MVC 3 you have to remove the WebMatrix.*.dll from _bin_deployableAssemblies and bin folders respectively.