on the manage domains page in the dreamhost panel does the domain show as "Fully Hosted" in the web hosting column? There is a user shown there also, is that the same user you are using to ftp?
finally, is this a new registered domain? Are you getting a DNS failure when the page fails to load, or is the server responding with anything? It may be that DNS for your domain is not yet fully propagated yet. If its been more than 12 hours you can force a refresh on the DNS tab in the panel.