Why do some embedded hyperlinks go to a 404 page?

When I click on some of the embedded links in a tweet, it pushes me to a "404 Not Found" page instead of the linked page. It looks like other tweeters can successfully click on the links, but not me. Not sure what's the issue. I didn't see anything in your "known issues" knowledgebase that was this issue. Here's a one of the people's accounts I can't see their tweeted hyperlinks: http://twitter.com/lilithsaintcrow . This is a new issue to me.