pc grapic card isue?

hello i seem to have a graphics card issue and i am not sure how to fix it
what happens is the computer will blue screen at any random time and it will say dumping physical memory to disk and will load till it gets to 100% and then i ususly shut it off as it will stay at that screen if i do nothing when i restart it will work fine untill it dose the same thing at any random time heare is more info on the problem

Problem signature:
Problem Event Name: BlueScreen
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 2057

Additional information about the problem:
BCCode: 1a
BCP1: 0000000000041790
BCP2: FFFFFA80065D9A50
BCP3: 000000000000FFFF
BCP4: 0000000000000000
OS Version: 6_1_7601
Service Pack: 1_0
Product: 768_1

Files that help describe the problem:
C:\Windows\Minidump\120813-43945-01.dmp
C:\Users\user\AppData\Local\Temp\WER-92087-0.sysdata.xml

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anyone have any idea what the error is and how to fix it thanks