After getting a SONY VAIO VGN-FS315S with the following config:
Intel(R) Pentium(R) M processor 1.86GHz
LCD X-Black15,4 screen with 1280x800 resolution
1024 MB RAM
100 GB Hard drive
DVD-/+RW optical drive
NVIDIA GeForce Go 6400 (128 MB)
Realtek High Definition Audio Soudcard
Intel PRO/100 VE (wired network interface)
Intel PRO/Wireless 2200BG (802.11b/g standards)
I installed Warcraft III Frozen Throne and after half hour of playing, I was getting errors like:
BCCode : 100000ea BCP1 : 855E9810 BCP2 : 843AC848 BCP4 : F7A57CB4
BCP4 : 00000001 OSVer : 5_1_2600 SP : 2_0 Product : 768_1
among with the "System has recovered from a serious error" message.
The same thing was happening in Civilization 4.
In the benchmark and stress programs, all was fine, I was not getting any error. I was in the point of returning the laptop, but I have found one some forums something about new drivers and I gave one more chance.
I downloaded the NVIDIA Forceware 82.10 (x32) drivers from
http://downloads.guru3d.com/download.php?det=1227 and things are much better now, almost no more crashes.
So it was definitely a video card problem, I assume some kind of overheating since it was happening only after some minutes of playing.