alias database unavailable

["Chris Dunbar" <postfix@xxxxxxxxxxxxx>]

Hello,

I am running 2.2.5 on a Solaris 9 server. All was well until I pointed the
server to a new NIS domain last night. Today the users reported that they
were  not receiving their e-mail. a check of the logs shows this:

(alias database unavailable) after each attempt to deliver a local
message. This server runs a single domain set up in a virtual map file.

I'm not sure what alias database it is unhappy about. Any ideas?

Thanks,
Chris Dunbar