Depending on his version of Windows, you want to access his Task Manager.
If he has XP Pro, it will be by typing <Alt><Ctrl>Delete>
If this has Vista, <Alt><Ctrl>Delete> will bring up a page that will display a few choices. Select Task Manager.
Click on the Processes
Click on
CPU
You will need to click on it twice, to bring up the highest percentage to the top of the list.
This will tell you what process is hogging the
CPU.
Reply to this message with the "Image Name" and the "User Name".
If he has Vista, you can stretch the window, "wide".
The right most listing is "Description".
Relay that information to us as will.
With the data, we should be able to give you a course of action.
Suggest you introduce your friend to our service, so you will not be committed to always having to help him yourself.