Do you have a URL for the hub that you are trying to publish? When you first start a new hub and input a title for your hub, the URL of your hub is automatically whatever title you put. However, you can edit the URL and change it such as shortening it or only putting the keywords of your hub.
If you're getting the error that you mentioned, perhaps you haven't inputted a URL for your hub yet. Put your chosen URL for your hub then try publishing it again.
If you're still having problems, then you can try contacting HubPages about this via the help wizard. Here's the link for that: http://hubpages.com/help-wizard/ . Hope this helped.