There could be several reasons from this.
1. The web site is in the process of rebuilding and has not completed. The fix for this is to try again later.
2. This page on the web site no longer exists because the site has removed the page. In this case, try another searched link.
The world wide web can retain pages on the many search engines (like google, norton search, yahoo search) for months. When you conside the billions of pages that are now on the web, pages are not added or removed in seconds. There is a saying, once on the web, forever on the web.