Thanks for the help.
> Shut down the corrupted database and make a physical backup of it.
>
I did it before trying anything.
> Check the disks and memory on the machine where the problem occurred.
>
We are using virtual machines (VMWare). I will ask then to investigate
anyway.
> You can try to salvage data from the corrupted tables, either
> using "zero_damaged_pages" (but that will only work if the page
> header is corrupted), or by excluding problematic tuples by their
> "ctid".
>
Thanks will try.