This is almost certainly a power outage. I don't expect to see any domain seizures since just about every book (that I know of) migrated to a non .com (which registrations are subject to US jurisdiction, though not necessarily the content themselves depending upon how the site is structured), though other authorities could seize other domains but this is highly unlikely given most countries' penchant for legalized gambling.
A fiber cut could have the same impact as well but given the vast amounts of fiber laid in the Caribbean, I think that is less likely.
That said, only the log-in is failing so i'm guessing there is some sort of internal error (power, machine failure, etc). Any site making this kind of money should be fault tolerant.