My hp pavilion laptops video card messing up

i use an s video cable to plug up my windows vista laptop to our plazma big screen, and every time ill either have an automatic shutdown followed by some blue screen, or my screen will go completely black.when it comes on the tv it changes my screen resolution to that equal of the screen size shown on windows 95 and 98(makes everything super big turns screen resolution as low as it can go).i want to keep using it on my tv, but not at the expense of my laptop!
any products i can use, or helpful advise will be nice right now ty