Redirect to Full URL with Foms Authentication

[Tigertoes]

I have been using forms authentication with no problems.
However, I now want to navigate around various forms on my site using FULL URLs (i.e http://host/xxx/yyy.aspx etc). When I hit the redirect code, it obviously tries to redirect to the required form, BUT, forms authentication kicks in again and we're redirected to the Login page.

e.g.
This line works:
response.redirect("DetailForm.aspx") and we're redirected to the detail form

This line:
response.redirect("http://server/folder/DetailForm.aspx") takes me to the login page.

Any ideas?

PS. The reason for this is that my 'live' site uses SSL so I need to redirect to the full https: path. My dev site does not have a SSL certificate so I need to parametize the protocol name using Web.Config values.