BSOD in Windows 7 Ultimate 64-bit

I have a Windows 7 Ultimate 64-bit, 2 x 2GB DDR3 RAM, Intel Core i5 2.8Ghz, M.B. Intel DH55HC series machine which gives me the following BSOD. The BSOD comes up randomly for no apparent observable event identifiable to me.

Error : A problem has been detected and Windows has been shut down to prevent damage to your computer.

The problem seems to be caused by the following file: ntoskrnl.exe

PAGE_FAULT_IN_NONPAGED_AREA

If this is the first time you've seen this stop error screen, restart your computer. If this screen appears again, follow these steps:

Check to make sure any new hardware or software is properly installed. If this is a new installation, ask your hardware or software manufacturer for any Windows updates you might need.

If problems continue, disable or remove any newly installed hardware or software. Disable BIOS memory options such as caching or shadowing. If you need to use safe mode to remove or disable components, restart your computer, press F8 to select Advanced Startup Options, and then select Safe Mode.

Technical Information:

*** STOP: 0x00000050 (0xfffffa900395d270, 0x0000000000000000, 0xfffff80002df3070, 0x0000000000000005)

*** ntoskrnl.exe - Address 0xfffff80002cbf740 base at 0xfffff80002c4f000 DateStamp 0x4cc791bd

Already tried: disabled BIOS caching shadowing etc, removing one of the RAM modules, installing Windows 7 Professional 64-bit (different than what is on the machine).

Try running Memtest86+ to test for bad memory.

If you are still having problems, try running in safe mode and running prime95 or a similar stress testing tool. If the bluescreen doesn't show up, it is most likely a bad driver, however, if it does show up, you could have a bad motherboard (or unlikely, but a bad processor).