problem with man?

[Rob Browning <osiris@cs.utexas.edu>]

For quite some time now, any man keyword search ends with:

apropos: warning: can't read the fallback whatis text database.
apropos: /usr/X11/man/whatis: No such file or directory

It started a while back, and I assumed that it was a buggy package,
and that it would go away when a newer one was released, but it's been
a while (and many packages) and the problem remains.  It's not just
one system either, it's happened to a couple of the machines I
maintain.

Who generates the whatis file?

Thanks
--
Rob