I've been trying to add a website to google's add site http://www.google.com/addurl/ but it will not work. Is it my computer, or is anyone else having this problem?
ADD URL only is needed by new or smallest sites all others get googlebot visits by the thousands daily all others have RSS feeds or other means to instantly promote new pages if you are new - then you need to make sure you have at least a few dozen quality backlinks pointing to that new site, then G will honor you if no one links to that site, why should G wast its valuable resources ? hence among many other options to promote a new site could be the use of your signature links on a high traffic forum such as HERE
Did you sign up for Google Webmaster account? You can learn more about indexing and adding your site to google as well as to know better their guidelines to rank well.
sometimes google add url showing problem but you can try this for new site otherwise google will take automatic