Your site seems to be working fine for me, with or without www.
Generally you can force the site configuration to be rebuilt simply going to the domain edit page and save it again, and that might clear up such problems - given you wait at least 15 minutes. Other times it might help to have a third-party check the site. If you can't call someone on a different ISP/state/continent, then try sites like http://web-sniffer.net/ and see if the error comes up there. If DreamHost changed the IP address of your site, your browser might not catch on until you restart it or reset your connection.
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