I'm using UrlRewriter to rewrite some blog urls. I think this may have to do with the Css file. My structure looks like this: App_Themes/Default/images App_Themes/Default/DefaultStyle.css In my .master, I linked the css like: href="~/App_Themes/Default/DefaultStyle.css" All references in the Css file to images look like this: url(images/blah.jpg) My rewrite statement is like this: <rewrite url="/users/([a-zo-9]+)/blog/(\d{4})/(\d{1,2})/(\d{1,2}) to "~/Blogs/ViewBlog.aspx?username=$1&amp;yr=$2&amp;mon=$3&amp;day=$4" processing="stop" /> I get the error when navigating to for example: /testuser/blog/2007/11/28. I also have some rewrite statements that just goto the year so using /testuser/blog/2007. That works. Also the month works. It seems when it gets 3 levels deep it has a problem. I've read on the internet and i've also added this to my config file: cookieless="UseCookies" in the authentication/forms section. Does anyone have any solutions?