Gx623 gfx problem

Question

Greetings, i own a Msi Gx623 that came pre installed with windows 7 32bit, it worked fine and i could play World of Warcraft just fine but after a while i decided to try out some other games (borderlands, assassins creed, battlefield) but i've encountered a problem after playing these games for a while, they all end up crashing the computer... First the screen would go all black and flash pretty fast and all input would stop responding although the sound still continued wether it was ingame sound or music but after 10-15 seconds the sound would also crash and lock up in a small infinite loop sounding like a scratched music cd...
The only way to get the computer working again is doing a hard reset
I consider myself pretty good with computers so i started with checking out if there were new drivers, windows update said there was so i decided to try it out but no luck the games still crashed so i checked on the msi driver page and installed that one, still no luck...
Then i went to ati's site to get the newest driver but it wouldn't let me install it, so i got the "Ati mobility modder" application, modded the install acordingly and i could install without a problem but the problem still was there...
Oh well, maybe a fresh OS install would help? so i acquired me a Windows 7 64bit ultimate and installed it, now the drivers here was a little more tricky as MSI apperently don't support 64 bit for this laptop and therefor denie us the use of 700mb additional ram , anyway i tried the windows update methode and started up a game but still no luck :( did the Ati mobility modder trick again on the newest 64bit drivers from ati but no luck this time either.
Fine either it's a driver issue that haven't been fixed or it's not a driver problem, so I checked for the temperature of the GPU with AMD gpu clock tool and instructed it to save a log file with temps, after 20min of playing a game without crashes i closed it and looked at the max temp: 78 degrees, that seems fine as the limit is 90 for a gpu iirc?
The most recent and strange thing that happend is that i overclocked the card slightly with the AMD Gpu clock tool and it ran Borderlands fine for a couple of hours although it usually crashes once a hour
What i've thought about doing but haven't done yet:
Installed a different os like xp 32bit
bios flash the card (i don't dare doing it though)
Anyway, anyone that have a clue about what could be wrong? the last thing i know that could be wrong is a hardware failure...
Oh btw i was looking at contacting MSI support but where do i find the serial no. of the laptop? i've looked all over the laptop but i can only see the 2 model numbers (gx623 and MS-1651)

Answer 1

@zagitta and all with this black screen + hanging sound crash problem:
My best friend bought the same Notebook (MSI GX623 with ATi 4670), he had the same problem with getting a black screen with hanging sound, after a few second sound also was gone.
Only a restart of the notebook was possible.
We tried many different drivers 9.11 -> 10.3 (also Beta Drivers), with no improvement in stability.
Tools like Furmark or other Stresstests runs fine without crash.
Games with Source-Engine (DOD Source, CS Source, Team Fortress 2, ...) mostly crashed in the 10 mins, otherwise some Games (COD MW 2, Torchlight, Aliens vs. Preator) crashes later (but the also did).
After 2 RMA's (changed Cooler, changed Graphics-Chip, Technicans didn't find a problem) there was no change in the situation, the "Gamer"-Notebook still crash.
Yesterday my Friend sayed, that Battlefield Bad Company 2 was the only Game which didn't crash since he played it on the Notebook.
Because this i monitored the GPU-Core Clock and Memory-Clock with GPU-Z while playing DOD:S and BF BC2, i could see that the Core-Clock and the Memory-Clock was at 3D-Speeds in BC2 but not in DOD:S.
In this moment i remembered on my old System with 2 PowerColor 3870 in Crossfire, there was a similar problem with crashes in Battleforge because i modified the GPU-Bios to get 2D-Clock in idle (Powercolor-Bios was piece of crap), the GPU-Clocks changed multiple times between 2D and 3D Clocks while playing => Crash.
Because this i installed ATi Tray Tools on his notebook, created 2 Profiles (2D clocks & 3D clocks), in the settings of ATi Tray Tools i configured to use the 3D Profile in all 3D Games and the 2D for non-2D Mode.
Now the GPU uses the 3D-Clocks in all Games, no crash since ATI Tray Tools manage the GPU-clocks!!
In my opinion the GPU Bios of the 4670 in the MSI Notebook is crap, no driver-release would help you because of this!
I hope this could help you!
PS: Sorry for my bad english
Greets from Austria