It sounds like the problem is occurring when power managment or a screensaver is kicking in.. As such, drivers may be the culprit.. Be sure to visit the motherboard manufacturer's website and download/install the most recent motherboard/chipset drivers for your machine. Likewise for all other drivers on the machine and it's possible you need an updated BIOS for the motherboard.. Be sure they are all current.
Hope this helps.
Grif
Everytime I'm not using my desktop for around 10 minutes it will blue screen and restart. But when I use it I don't every get them. I can't figure out why it does this. I'm just assuming it might be some type of hardware error since I recently built this desktop.
Problem signature:
Problem Event Name: BlueScreen
OS Version: 6.1.7600.2.0.0.256.1
Locale ID: 1033
Additional information about the problem:
BCCode: 3b
BCP1: 00000000C0000005
BCP2: FFFFF88004970817
BCP3: FFFFF8800805A900
BCP4: 0000000000000000
OS Version: 6_1_7600
Service Pack: 0_0
Product: 256_1
Files that help describe the problem:
C:\Windows\Minidump\012311-20436-01.dmp
C:\Users\Devon\AppData\Local\Temp\WER-1864040-0.sysdata.xml

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic