1. Right click on the task bar (bar with the start button on it)
2. Left click on task manager
3. Click on processes tab
4. Click twice on CPU heading.
This will show you at the top of the list what process is causing 100% cpu time. Once you know what it is, you can try and get rid of it. It is normal for system idle process to be a large number, don't worry about that.
The process that is taking up lots of time, you can try and right click on it and then end process tree. Just a warning, if you end a process that is system dependant or application dependant you can crash your system.
Good luck.
jg613@pacbell.net