Synaptic not feeling well

This message is posted two two lists as I am quite uncertain as to which of them would be less unappropriate. Today, when I went to open synaptic from the kde menu on FC3, I noticed that it was missing! So I opened it from a terminal, but cannot update- no matter what I try to update I get this error (or one vey similar): APT system reports: E: Unknown signature /var/cache/apt/archives/taglib_0%3a1.3.1-1_i386.rpm: (SHA1) DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#1ac70ce6) E: Unknown signature /var/cache/apt/archives/amarok_0%3a1.1.0-2_i386.rpm: (SHA1) DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#1ac70ce6) E: Error(s) while checking package signatures: 0 unsigned package(s) 2 package(s) with unknown signatures 0 package(s) with illegal/corrupted signatures Um, what can I do? I should probably mention that I have about two weeks of linux experience under my belt. Thanks.