Windows 7 Blue Screen of Death for unknown state

[PPAAOOLLOO]

Hi All I'm Paolo from Italy.
I have a strange problem with my Pc (window 7 64 bit).

Sometimes (2-3 times a day) I have a BSOD.
Sometimes I have this problem when I open the "Computer" icon in the Start folder.
Sometimes I have this problem when I try to search a file.
Sometimes I have this problem when I listen an mp3.

I start thinking that it is a RAM problem.
I run MemTest86 but it detects no errors.
I change my 2x2Gb RAM with other 2 but I have the same BSOD.
I try to connect RAM to other slot, but I have the same BSOD error.

I try to update Video Driver, but I receive the same problem.
I try to scan my Pc with Avira antivirus, but no virus detected.
I try to scan my Pc with MaleWareBytes anti-malware but no infections detected.

I try to scan my HD with the Western Digital tool (Data LifeGuard Diagnostics) but no problem detected.

And I still have BSOD.
What can I do?
Here you are the BlueScrrenViewer Infos: http://i45.tinypic.com/2urthld.jpg

Can you please help me?
Thanks in advance
Best regards
Paolo

 

[GeneralHiningII]

Link Removed

Follow the link and instructions here: Link Removed
To get a more accurate description of the events.

Memtest86+ run: how long did you do it for? Normally you need at least seven hours for it to run properly.

Have you checked your motherboard manual to make sure that you're using the correct RAM slots (usually 1 and 3, 2 and 4).
Also make sure you aren't forcing the RAM sticks into the slots - gentle press and it should click.

When you're updating your video driver:
a) Are you sure it's the correct one? (certified by the manufacturer and Microsoft (WHQL), for your product)
b) What are you doing when the BSOD happens? During the download, during the install or..?

Looking at the bluescreenviewer images (still, use the tool with the link here: Link Removed
a) NTFS.sys - something wrong with your hard drive (in my experience anyway) - use these tools Link Removed to properly check your hard drive. (also hdtune.com for even more stuff to install)
b)_ntoskrnl.exe - not sure about this yet since I don't have any of your system information. Once more, use our own tool to get the dumps from your BSODS.