We are aware that some websites hosted on the MIA2000 server (one of our Shared Hosting servers in Miami) are intermittently reporting a "503 Service Unavailable" error.
We have this resolved for most of the sites already and are still working on it. We'll update this status incident once we have a full resolution on this.
UPDATE: This is now resolved. If you are still experiencing any issues please open a support ticket and we'd be happy to assist.