Getting Video Hardware Error While Playing Games Only

Hi, I have an Acer Aspire 7720 laptop and I am having some video hardware issues with it. When I got my laptop a year ago it ran perfectly on any game/any setting. After about 6 months I started to have errors. I am playing Warhammer Online and World of Warcraft, and WoW is not graphically intensive at all. I play both on the lowest settings or else my laptop freezes or has a critical error. My fiance works for Geek Squad and he couldn't figure out the problem so we sent it out to the service center and they replaced the video card and ram. The same problems are occuring only when I am playing games. I am about to send it out to the service center again to get the video card and motherboard replaced because I can't figure out what other "video error" it could be. All the drivers are up to date! Under problem reports and solutions I have months worth of errors that say:

Video Hardware Error
Description:
A problem with your video hardware caused Windows to stop working correctly.

Problem signature
Problem Event Name: LiveKernelEvent
OS Version: 6.0.6001.2.1.0.256.1
Locale ID: 1033

Files that help describe the problem
WD-20081025-1553.dmp
sysdata.xml
Version.txt

Extra information about the problem
BCCode: 117
BCP1: 86990008
BCP2: 8F0069B0
BCP3: 00000000
BCP4: 00000000
OS Version: 6_0_6001
Service Pack: 1_0
Product: 256_1

A couple more files:

WD-20080813-1856.dmp
WD-20081011-1226.dmp
WD-20081011-1032.dmp
WD-20080923-1801.dmp
etc.

Any Ideas?


Specs:

Operating System: Windows Vista™ Ultimate (6.0, Build 6001) Service Pack 1 (6001.vistasp1_gdr.080425-1930)
Language: English (Regional Setting: English)
System Manufacturer: Acer
System Model: Aspire 7720
BIOS: Default System BIOS
Processor: Intel(R) Core(TM)2 Duo CPU T5250 @ 1.50GHz (2 CPUs), ~1.5GHz
Memory: 3070MB RAM
Page File: 991MB used, 5045MB available

Card name: NVIDIA GeForce 8400M GS
Manufacturer: NVIDIA
Chip type: GeForce 8400M GS
DAC type: Integrated RAMDAC
Device Key: Enum\PCI\VEN_10DE&DEV_0427&SUBSYS_011E1025&REV_A1
Display Memory: 1009 MB
Dedicated Memory: 241 MB
Shared Memory: 768 MB
Current Mode: 1280 x 768 (32 bit) (60Hz)
Monitor: Generic PnP Monitor
Driver Name: nvd3dum.dll,nvwgf2um.dll
Driver Version: 7.15.0011.5616 (English)

Good thing I bought the service plan. I'll send it to the service center 2 more times and get another comprable model due to no lemon. Thanks for the info.