weird warning about packages being unauthenticated from package update manager....

[Michael Fothergill <michael.fothergill@googlemail.com>]

Dear Folks,

I just got a message from the package update manager:

It says" Warning You are about to install software that can't be
authenticated! Doing this could allow a malicious individual to damage
or take control of your system."

I would be upgrading 25 packages if I clicked on the apply button but
I haven't done it because of the warning.

I don't remember getting this kind of warning in the past.  I would be
upgrading openoffice and opera (this I think is a non free commercial
browser and maybe that is causing the warning here... not sure and
ttfopensymbol).

What might be causing it?

I am using Firestarter and AMD64 Lenny.  Comments appreciated.

Regards

Michael Fothergill