Error Message - What is it trying to tell me?

My pc is an HP DX2300 running Windows XP pro.  
Windows Essentials is installed on this pc  It reports all updates are installed.
So, I am confused.  The error message  (see below) is displayed many times in the Event viewer.

What is this message trying to tell me?

==================  The message ===================
Microsoft Antimalware has encountered an error trying to update signatures.
     New Signature Version:
     Previous Signature Version: 1.121.385.0
     Update Source: Microsoft Update Server
     Update Stage: Search
     Source Path: http://www.microsoft.com
     Signature Type: AntiVirus
     Update Type: Full
     User: NT AUTHORITY\SYSTEM
     Current Engine Version:
     Previous Engine Version: 1.1.8101.0
     Error code: 0x8024402c
     Error description: An unexpected problem occurred while checking for updates. For information on installing or troubleshooting updates, see Help and Support.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.