BSODs: Corrupted main system's files or drivers?

Hello there. My PC has been suffering some random issues lately and I'm not sure about what could be the cause of them.
Sometimes my PC becomes a bit unstable when I do certain stuff (for example, when I scan for virus) , Aero theme goes "poof" and the system ends up freezing, sometimes with a BSOD, sometimes not.

Restarting my PC doesn't work. Every time I restart after having that issue the system gets a lot of random BSOD and errors (related with the system's drivers, some of them end up closing themselves) after loading Windows, so I have to turn my PC off and turn it on again instead.

Some of the BSODs contain messages like: PFN_list_corrupt, PAGE_FAULT_IN_NONPAGED_AREA, ntfs.sys

I have cleaned my registry with CCcleaner (which caused lots more stability in my system) and checked my RAMs with memtest 86 (No errors). I've been gettting some small errors with programs which used to work perfectly, like Steam or Photoshop though.

The dump of the different BSOD errors says that they're caused by the following drivers: nvstor64.sys, Ntfs.sys, nvstor64.sys and ntoskrnl.exe among others.

Sounds like one of my drivers or main system's files got corrupted or something like that? Or perhaps the hard drive is about to die? They only "changes" I made to my computer before this issue were installing a bunch of Steam games and add an external hard drive, because I was always running very short of free disk space.

Just in case, these are my PC specs:

Asus Crosshair
AMD X2 5200+
ATI HD 4870
2x2GB RAM Crucial Balistic
SO Windows 7 Ultimate 64 bits

Yikes. This sounds like it could be a number of things. Since you've singled out the drivers, have you tried uninstalling and reinstalling the ones that you listed? Otherwise, you could try to do a system restore in safe mode and see if you're able to find a point prior to getting the stop error.

-- Ryan
Windows Outreach Team