my screen broke on my Vaio notebook.. i have tried to directly plug in a monitor to the notebook but it starts up i hear the sony start up sound but get blank screen then the Windows XP OS shows on my screen with a loading bar underneath it then the screen goes blank. i am amble to type my password to long in and the computer starts but still blank screen. i have also tried with a KVM switch same thing happens. any ideas why the screen cuts out after the OS loads???

Hello Nick
Most laptops have a function key to switch between the built in, an exterior monitor, or both.
On My Gateway, it is f4. On my older Toshiba it was f5.
According to your owner's handbook, your switch is f7.
http://www.docs.sony.com/release/VGNS400-T300series.pdf
Most laptops I have seen also have a little symbol on the various function keys that will give a hint regarding its function.
I hope this helps.

thanks.. worked right away lol