Just came across this while developing something on vista 32bit rtm(6000) Using SetWindowHookExW to create a hook w/ the WH_CBT type.
Then in the hook callback, when the nCode is HCBT_CREATEWND, cast the lParam to a LPCBT_CREATEWNDW. Set the hwndInsertAfter of the member of the LPCBT_CREATEWNDW to HWND_TOPMOST, and return. The system will crash, a blue screen w/ no info is displayed. You get a critical shutdown message next time you reboot.