O. S. - Microsoft Windows XP Home Edition
Ver. 2002
Service Pack 3
CPU 2.00 GHZ 1.99 GHz
Ram - 640 MB
Dell Dimension 2350

After downloading priority updates for my OS through the Microsoft web site on March 31, 2009 I noticed that other updates had been downloaded however for whatever reason they were not being installed!  I had to manually shut down my computer whereas I had always used the Start>Turn Off Computer> option before.  When noticing that the installation of the update wasn't being installed, I turned off my computer through the Surge Protector outlet.

The last updates installed were,
1.  Security Update for Microsoft XML Core Service 4.0 Service Pack 2 (KB 954430)
2.  Update For Win XP (KB 961118)
3.  Microsoft .NET Framework 3.5 Service Pack 1 and .NET framework 3.5 Family Update (KB 951847)x86

I remember that these updates were in excess of 200 MB and took well over 2 hours to download.  I don't know what happened, but will appreciate any help you could give me concerning this problem.   I ran all of the respective scans and no virus/malware/adware was detected. 
Thank you in advance of your suggestions.

Sandan