dxgmms1.sys BSOD - Left 4 Dead 2

Hi!

I recently upgraded to Windows 7 x32 from Windows XP x32
I've had the same BSOD three times now, fairly regularly, but also random

All three times it happened while playing Left 4 Dead 2.
The thing is I can't recreate it, it started about 2 months ago, but I ignored it and just let it do it's thing, but a week and a half ago it really got to me so I formatted my CPU, I assumed this would stop it... needless to say it hasn't. I don't know what it is

If it means anything... I did originally install 64Bit windows 7 on the first day it came out but my computer didn't handle it too well so I dropped down to 32Bit.

I will try literally anything because this really is beginning to bug me.

My computer spec:
Motherboard: Winfast
CPU: AMD Athlon 64 X2 Dual Core Processor 3800+
GFX: Radeon X1600 Seroes
RAM: 2x 1024 MB

Any help to stop me from getting further BSODs would be greatly appreciated. Let me know if there's any more information I need to provide to help with the troubleshooting.

Attaching Minidumps

Thanks in advance.

Did the validation
How do i do a sfc?
I've wiped the hard drive previously
and i refuse to use torrents etc.

My brother has a PC that is identical to mine in every way that is less than 15 metres away from me, yet he is working perfectly. please i need a fix?

& i assume when you say wipe the hard drive you mean format but windows 7 doesn't seem to allow you to do a full format as it keeps the old files.

The only difference between mine and my brothers PC is that he didn't install 64 bit to start with

{Attached todays minidump}