Unexpected BSOD results in crash dump

Hello everyone I have had BSOD's occuring on a relatively frequent basis (one every 1-2 days), and have been unable to diagnose the problem. Computer was running fine for about a year before this started occurring. I am hoping it is just a driver issue of some sort, but in the absence of any real knowledge about these things I have uploaded the minidump file in the hope someone can tell me what the issue is. :)

My comp specs and operating system (if it helps) are

I5 2400
4gb DDR3 1333 Mhz
ATI 6850
Win 7 64 bit

View attachment 061712-11622-01.dmp

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