Vista crash

Hi Everyone. I am not sure i am in the right group but will give this a try
and maybe you can send me elsewhere if i need to be.

I have a toshiba P100 laptop with a T7400 processor, 1 gig ram. I upgraded
to vista Ultimate and it seemed to work fine for a long time. Last week I
tried to install a couple of games a friend gave me and my display started
flashing and going off so I uninstalled the games, but it made no difference.
I then decided, ok, now was the perfect time to reformat and go back to xp
but when I did that I found out I did not have half the drivers I needed to
to get the laptop to work, or connect to the internet to find them, so i put
Vista Ultimate back on, downloaded all my toshiba software again, and all my
Vista updates. I checked and i do not show service pack 1 being installed.
So here is my problem. My laptop seems to keep hibernating but will not wake
up. It does not shut right down but everything freezes and the screen shuts
off. I can hit any key or click the mouse as much as I want but nothing
happens, even if i leave it 5 minutes. I have double checked the toshiba
drivers for updates.
The only other thing I will add is I added a 26 inch samsung Tv for a
monitor, but do not think that is making the problem.
Anyone have any suggestions as to what my problem may be, or how to fix it??
Thanks in advance.
Lviv