Weird number of messages on server

[giglio robbo' d'acciaio]

Maybe a gnus bug, i don't konw. By the way, when I try to subscribe a new
group from my server here it is what I get in th summary buffer:

     5843864: it.arti.cinema

I think that no group in the whole solar system has nearly 6 millions of
messages, moreover if I try to browse this groups gnus hangs up telling me
that it runs out of memory (no surprise) and suggests me to use 'M-x
save-some-buffer' command.

Any clue?
Thank's in advantage.
-- 
Bologna:
        Arrestate otto persone nella toilette di un autogrill.  Stavano
urinando in luogo pubblico.
                -- Panfilo Maria Lippi (Daniele Luttazzi), "TABLOID"