Given your description of the problem, I’m not sure there is much you can do other than to wait for a reply from support.
You did not say how your browser demonstrates that the sites are down: Do they time out? Do you receive any kind of an error message?
In some instances, sites can be “fixed” using the Control Panel Domains–>Manage Domains screen and clicking “Edit” to the right of the domain, then “saving” without actually making changes will cause a reconfiguration of the domain and solve the problem. This is particularly true if you are receiving an http_config error.
It is also possible that your sites are impacted by the earlier file server problem reported on Dreamhoststatus.com; since you have contacted support there is nothing ore you can do if that is the case. Good Luck!