Vista - Windows Defender Updates

Hope someone here can help.
In the last 5 days I have noticed my definitions for window defender KB915597 is at 1.43.801.0 and hasn`t changed at all... Generally i have seen defender updates definitions install without any problems , sometimes several times a week . Both my PC and my wife are Dell desktop machines on Vista Home Premium Edition IE 7 SP 1 for several months and the updates were being installed without any problems until the last one on Sept.26. Nothing in the configuration of Windows Update - Control Panel - Change setting has been adjusted in months.
Has anyone else expierenced this and know what is causing the no updates for defender. One machine has the Symantec anti-virus expired and the other has the McAfee expired but that shouldn`t be the cause since they have been expired for several months and definitions were being installed in the background for months , unless there is some connection now.

thanks for any ideas
anderson

I sometimes find Windows Defender goes into "sleep mode".Try this link from Major Geeks.It is the latest Windows Defender update,according to the site:

|MG| Windows Defender Antispyware Definition Updates 1.45.70

Hi,

You might try updating to the latest version of WUAgent

How to obtain the latest version of the Windows Update Agent to help manage updates on a computer

Hope it helps

SIW2