video crash after few second

Hi,

tks for the best site in all the web.

I have a MacBook 17" hi-res screen 28 month old...

it starts and after few seconds (often before system totally started) video make vertical lines and crash.

Sometimes mouse continue works.

If the MacBook starts as firewire disk it works for hours

What I tried:

change both memory modules

exit outdoor (-4 celsius)

boot from usb disk (tiger or leopard)

boot from dvd (leopard or snow)

nothing changed!

sometimes after apple-alt-P-R it works a minutes or two...

screenshot:

http://www.planete-i.fr/mac.JPG

answer:

tks,

but NO hd problem....

and bad video cards mean all logic card :-(