We came across an issue recently where automatic updates caused a windows 2003 server to run at 100% CPU continuously.
Even after the server was rebooted the CPU spike right back up to 100% CPU.
The first thing we did was check task manager and the SVCHOST.exe service was responsible for the High CPU, we noted the PID down of the process and then run the following command to find out what service was responsible for running the process.
The result of this was to show us that Automatic Update was responsible for running this process. So as a test we disabled the automatic update service and rebooted the server, the CPU then went back to a normal state.
I then came across the following update “http://support.microsoft.com/kb/927891/en”. I installed this and changed the automatic update service back to start automatically. After rebooting the server all the CPU issues went away