Update Problems

[catacon]

So I have Vista Home Basic on my laptop. It has been working fine and still is except for one issue, there is an update that never installs. I have tried to install this update about 20 times and it confirms that it has been installed each time, but it will always come back and say I need to install it. The update is "Security Update for Microsoft XML Core Services 4.0 Service Pack 2 (KB936181)" It was published 8/14/2007. Any ideas of how to get rid of this.

Thanks!