This is likely due to a bug in Service Pack 2's Data Execution Protection (DEP). Disabling this feature can resolve the issue. Here's how:

1. Right-Click on My Computer
2. Go to Properties
3. Click on the Advanced tab
4. Under Startup and Recovery, click Settings
5. Click on the Edit button
6. Notepad will launch with the boot.ini
7. Be careful editing this file, as this is a main component to booting Windows. At the end of the like that contains "Microsoft Windows XP..." there may be:

/NoExecute=OptIn
or
/NoExecute=OptOut

8. You'll need to change the OptIn or OptOut to AlwaysOff so it reads (this is case sensitive):

/NoExecute=AlwaysOff

9. Close the Notepad window, exit out of the menus, and reboot. The problem should be resolved.