Norton Internet Security 2012 is flagging calbasecomps.dll, a file in the latest Lightning update (which provides calendaring features for the Mozilla Thunderbird email program), as unreliable and quarantining it. It states that it's a "reputation-based" deletion, that "there are some indications that this file is untrustworthy." The deletion breaks the install of Lightning.
Is there something to this, or is this a false positive?