Fae, if you registered your domain within the last 48 hours, it’s normal that you will have intermittent problems accessing it; this is due to the fact that domains need to propagate through the Internet after they are registered, and this process takes time. The same is true if you have changed your name servers recently in order to move the domain from one host to another, for example.
In addition, even if you register a domain via your dreamhost control panel, let’s say while using your free domain option, you still have to ‘set up’ the domain under the “Manage Domains” section of your control panel. This is necessary so the web server knows that you will be hosting your domain with dreamhost. If you don’t do this, dreamhost only knows that you registered the domain with them, not necessarily that you are also hosting it there.
I hope this helped.