Latest Windows XP Update and SVCHOST.EXE problems??

Hello. My PC runs XP SP3 (HP Media Center) 3G of ram. It has been running fine lately with no issues whatsoever. This morning I booted up as normal. I noticed the familar Microsoft Update "yellow shield" in the lower right part of the task bar. I hovered the mouse over it and it read "downloading updates 0%". It never got above zero (nor could I open the update window). I pulled up task manager and SVCHOST.EXE was hogging 99% of my CPU. I closed everything and shut down and restarted. After the restart (thinking that it was a Windows Update issue) I went to the Microsoft Windows Update site and clicked on "Express" updates in an attempt to update manually. It started cycling (looking?) for updates and soon SVCHOST.EXE roared to life again and pegged the CPU to 99% usage (effectively maxing the CPU to 100%). The MS Update page never reached the point where it indicated I needed updates..it just kept cycling and looking. Once SVCHOST.EXE gets going (I've tried this update 3-4 times today) it doesn't stop (whether I close the Windows Update window or not). I have to shut down and reboot. When I shut down I see an "end program" prompt for RUNDLL.EXE which (when I try to "end") results in a "not responding" prompt. I have to end the program to shut down. As a precaution I've scanned with MSE, Malwarebytes, Spybot and SuperAntiSpyware and all were clean. No issues with MS Security Center either. I have never seen my computer behave like this before. At the time of this post it seems fine except when I attempt to update at the Microsoft Site. Was there a bug or an issue with the latest update?  Any thoughts appreciated. Thanks.