very typical bsod!

for the past month i have experienced blue screen about 5 times, i had re-formatted my HD several time the problem still persist, the strange part is the BSOD only occur when i'm watching video eg:youtube, window media player and the bsod is not constant it can happen within 20min of watching video or for the whole day nothing will happen , last night on purpose ran my window media player on some random movie let it repeat constantly and ran it overnight to test and the bsod did not occur after that i went online and watched some anime within 20 min it happen again! the typical part is it never happen when i m playing game or normal task it only occur when i had my video playing!

here is my specs its about 7 month old

INTEL CORE i5 750
GIGABYTE P55A-UD3
4GB DDR3 1333MHZ
PC 5870 1G
SEASONIC 620W
WINDOW 7 HOME PRE 64BIT OS

here is the recent BSOD code

==================================================
Dump File : 020511-20092-01.dmp
Crash Time : 2/5/2011 1:34:10 PM
Bug Check String : UNEXPECTED_KERNEL_MODE_TRAP
Bug Check Code : 0x0000007f
Parameter 1 : 00000000`00000008
Parameter 2 : 00000000`80050031
Parameter 3 : 00000000`000006f8
Parameter 4 : fffff800`028e34cb
Caused By Driver : ntoskrnl.exe
Caused By Address : ntoskrnl.exe+70740
File Description : NT Kernel & System
Product Name : Microsoft® Windows® Operating System
Company : Microsoft Corporation
File Version : 6.1.7600.16617 (win7_gdr.100618-1621)
Processor : x64
Computer Name :
Full Path : C:\Windows\Minidump\020511-20092-01.dmp
Processors Count : 4
Major Version : 15
Minor Version : 7600
Dump File Size : 274,264
==================================================

run DISKCHK with no error
done memtest for close to 8 hours with 8 passes error-free
checked the temps for processor its under 30 degree without load
GPU temps are running at 45 degree without load
done all window /driver updates
am using ATI 10.4
tried passmark burn in test 3 times to stress my PC but still there is no error
all component are at stock speed i did not overclock it at all

so far all the bsod only happen when i am watching video and it happen randomly , i have tried to AFK inside games for close to 2 days nothing happen but when i try to watch video after a random period of time BAM! BSOD

i am getting clueless i will really appreciate if someone can enlight me! i have tried all i could with all means ...