Domain has vanished?!

[Paul]

Hi,
    I am running in.named that came with Solaris 2.5 . I must confess
that I
am not really an expert with this. I have a problem where one of my
domains
seems to have vanished. I.e. no one can resolve it, in the sense that
when
they look it up they find it doesn't exist. I have checked it is
registered
(it is, has been for a year or so), and there are no billing issues
either.
My DNS config re this domain hasn't changed since last year sometime.
So
when I try and send a test from hotmail for example to a mailbox on
this
domain I get an error saying that no host can be found for that
domain.
    This problem started over the weekend apparently.
The domain is hba-uk.com btw.



Any advice would be appreciated.


Paul