I have a computer running 8.04.4. After a large number of updates, I can no longer run ubuntu-tweak correctly. The program states "This feature is only available in Gnome Desktop Environment" on most of the items.
I am POSITIVE that I am running the Gnome desktop.

Also, when I reload the repositories I receive the following error:
W: GPG error: http://ppa.launchpad.net hardy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY (then a hexadecimal number)
Are these two things tied to each other possibly?

Thank you for any input.