Taken from here.
On the My Computer icon right click with your mouse and choose Properties. (My Computer can be found on the desktop and/or the Start menu depending on how you have your Windows XP setup.)
A small window will have appeared called: System Properties. Look for the “tab” along the top called Advanced, now click it.
Now look for the section called Performance and click the button called Settings.
You will now see a new window appear called Performance Options, click the tab along the top called Data Execution Prevention and you should get the same window view as the image below.
- You may now choose to turn it off.