Any chance that's a 80072EE2 or 80072EE7 error?
If not, are you updating via WSUS? => http://social.technet.microsoft.com/Forums/en/winserverwsus/thread/76d599b5-11f1-476e-a9a3-50d7bc9b0b93
~Robear Dyer (PA Bear) ~ MS MVP (IE, Mail, Security, Windows & Update Services) since 2002 ~ Disclaimer: MS MVPs neither represent nor work for Microsoft