The package “XYZ.pkg” has an invalid signature.

Valued Contributor

I have a couple of computers running OS X 10.7.5 Lion that are receiving the following error message whenever any type of signed package attempts to be installed by Casper (and manually as well):

"The package “XYZ.pkg” has an invalid signature."

I was under the impression that 10.7.5 has the proper signatures to install signed packages. I checked the packages themselves, and they work find on the other Lion and Mountain Lion computers I have deployed. Any ideas on what I can do to resolve this, besides a re-image? Google hasn't been much help so far...