Solution
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Bug Check 0x101: CLOCK_WATCHDOG_TIMEOUT

This indicates that an expected clock interrupt on a secondary processor, in a multi-processor system, was not received within the allocated interval.

Basically, some hardware component locked up. The typical cause for this is overheating, so check temps and make sure they are in acceptable ranges.
Can't open your file. If your talking about a one time event then it could be a software glitch that caused the BSOD. It becomes a real problem when it happens continualy and you do want to take note of when it does and what the stop code is.
You can also go into the event viewer and see what was recorded there for the time it blue screened , sometimes it will tell you if it was a hardware conflict or software related.
 
try running memtest on your ram stick to see that the ram stick is fine. also open your pc make sure you blow the dust out of it. could be over heating from dust or a slow fan. check that the ram stick is seated. run cpu-z chech that the mb has set the ram speed up right. (spd tab will show the speed your ram can run at). if the speed or timing not right under load it can bsod.
also on older system you may have to bump the ram voltage up a little to make it stable under load.
 
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Bug Check 0x101: CLOCK_WATCHDOG_TIMEOUT

This indicates that an expected clock interrupt on a secondary processor, in a multi-processor system, was not received within the allocated interval.

Basically, some hardware component locked up. The typical cause for this is overheating, so check temps and make sure they are in acceptable ranges.
 
Solution
Bf3 is one game that will heat up your vieo card pretty good , what are the settings that your playing at and the resolution. You have a 6850 video card , does it have adequite cooling? Do you have a side panel fan? You can monitor the temps on the cpu and the video card and if you can't then take the side panel off and place a fan to blow directly onto the motherboard where it can cool both the videoo card area and the cpu aea and then run BF3 and see if you get the BSOD.