Any idea what this Synaptic message means?

Fri Feb 10 10:03:10 UTC 2006

W: GPG error: http://cn.archive.ubuntu.com breezy Release: The following
signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive
Automatic Signing Key <ftpmaster at ubuntu.com>
W: GPG error: http://security.ubuntu.com breezy-security Release: The
following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu
Archive Automatic Signing Key <ftpmaster at ubuntu.com>

--
Michael T. Richter
Email: ttmrichter at gmail.com, mtr1966 at hotpop.com
MSN: ttmrichter at hotmail.com, mtr1966 at hotmail.com; YIM:
michael_richter_1966; AIM: YanJiahua1966; ICQ: 241960658; Jabber:
mtr1966 at jabber.cn
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