It's an intermittent problem with our image servers as you're seeing. We fortunately do have some control over it here so we're keeping a close eye on things to minimize disruption of service.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .