0x8007041D - 2147023843 - ERROR_SERVICE_REQUEST_TIMEOUT
The service did not respond to the start or control request in a timely fashion
You receive a "0x8007041D" error when you visit the Windows Update Web site
http://support.microsoft.com/kb/902322
Can you update Defender manually via the Security Portal?
http://www.microsoft.com/security/portal/Definitions/HowToWD.aspx
~Robear Dyer (PA Bear) ~ MS MVP (IE, Mail, Security, Windows & Update Services) since 2002 ~ Disclaimer: MS MVPs neither represent nor work for Microsoft