Asp.net forms authentication cookie not honoring timeout with IIS7

Authentication cookies seem to timeout after a short period of time (a day or so). I am using Forms Authentication and have the timeout=”10080″ with slidingExpiration=”false” in the web.config. With that setting, the cookie should expire roughly 7 days after the user is successfully authenticated.

How to override/change FormsAuthentication LoginUrl in certain cases

Is there a way to dynamically change the LoginUrl of FormsAuthentication? What I have is the whole site protected by FormsAuth, but for some pages in a sub folder, I’d like to take the user to different login page, and have FormsAuth handle the ReturnUrl stuff. Is that possible or do I have to write my own redirect code for the sub folder cases?