STUDIO 1537 Shoutdown problem

Hi,

I have a Studio 1537 Laptop.

While I was watching some videos from Internet my laptop is shutting down after 10-15 minutes without any warning.

When I checked the event viewer I saw;

atikmdag Event id 43029 DAL and

atikmdag Event id 52236 CPLIB

Kernel-Power Event id 41 (63)

My operation system is Windows 7 Ultimate 32 bit.

Previously I had  Windows 7 Ultimate RC edition during that time I did not

have a problem but when I installed the official version this problem starts to occur.

I install Video Driver (By the way I did not find the Windows 7 driver so I install Vista 32 bit video driver) but it did not work. Nothing change.

What can be the my problem? How I can solve this problem.

It is really annoying me. Because of this shout down I am afraid of the damage the hard disk.

Thanks in advanced.