Hang ups and BSOD

Hey

My pc has started to crash occasionally -> it just hangs up and doesn't response to anything. Hang up comes always when i'm trying to play games -> basically i can't play BF3 more than few minutes before it hangs up and only rebooting helps. Pc also sometimes hangs up when it doesn't do anything. I need to often reboot several times to get the system up and sometimes the pc start's but my screen stays black ( i can hear the sounds).

Usually i don't get any error report, but twice i have managed to see the following report:

Description
A problem with your video hardware caused Windows to stop working correctly.

Problem signature
Problem Event Name: BlueScreen
OS Version: 6.0.6002.2.2.0.768.3
Locale ID: 1035

Files that help describe the problem
Mini121511-01.dmp
sysdata.xml
Version.txt


View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Extra information about the problem
BCCode: 1
BCP1: 0000000077726CBA
BCP2: 0000000000000000
BCP3: 000000000000FFFE
BCP4: FFFFFA600792DCA0
OS Version: 6_0_6002
Service Pack: 2_0
Product: 768_1

Click to expand...

and few times his one:

Description
A problem with your video hardware caused Windows to stop working correctly.

Problem signature
Problem Event Name: LiveKernelEvent
OS Version: 6.0.6002.2.2.0.768.3
Locale ID: 1035

Files that help describe the problem
WD-20111211-1505.dmp
sysdata.xml
Version.txt


View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Extra information about the problem
BCCode: 117
BCP1: FFFFFA80044840B0
BCP2: FFFFFA60025816DC
BCP3: 0000000000000000
BCP4: 0000000000000000
OS Version: 6_0_6002
Service Pack: 2_0
Product: 768_1

Click to expand...

I have made clean install for new Nvidia drivers and checked the temperature of GPU & CPU, didn't see anything unsual.

Vista . . . - x64 - the original installed OS on the system? yes - OEM - What is the age of system (hardware)? Build 2008 summer - What is the age of OS installation? Been running since 2008 without new installations