I had never seen that before, that the Update manager shows me a lot of software updates to install, but does not let me select them and offer me only a partial update.

I tried to use [Check] and got An error occured:
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 248DD1EEBC8EBFE8
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 6AF0E1940624A220
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 60D11217247D1CFF
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 90345E8D2FEF0CE2
Could this be the reason for the partial update? How can I fix it?

bye

Ronald