Issue with URL Tampering

Hi,

I have an issue with URL Tampering.

For example, lets take this url http://www.cinemax.co.in/Inner/AboutUS.aspx
This is the website of Cinemax.

Now, if I change the url as follows
http://www.cinemax.co.in/Inner/AboutUS.aspx/script/abc.aspx,
since the above resource doesn't exist, the user should be redirected to Error Page(provided customerrors option is On in web.config) or the message "the resource cannot be found" must be displayed.

But, in this case, the same loads again without any styling and formatting. Also, images in the page are not displayed.

I am facing similar issue with my web application.

Please let me know what am i missing ?
How to solve this issue for the entire web application??