Hello Gabriele.
The display driver you are using is kinda old.
Code:
lmvm atikmdag
start end module name
fffff880`04a4b000 fffff880`055fe000 atikmdag T (no symbols)
Loaded symbol image file: atikmdag.sys
Image path: \SystemRoot\system32\DRIVERS\atikmdag.sys
Image name: atikmdag.sys
Timestamp: Wed Jul 04 10:46:13 2012 (4FF3D19D)
CheckSum: 00B618E2
ImageSize: 00BB3000
Translations: 0000.04b0 0000.04e4 0409.04b0 0409.04e4 Update it.
Latest AMD Catalyst Video Driver for Windows 7
Uninstall Avira. Use
Microsoft Security Essentials as your antivirus with windows inbuilt firewall, and
free MBAM as the on demand scanner.
Download and install those, and then run full system scans with both of them, one by one.
Test your RAM modules for possible errors.
How to Test and Diagnose RAM Issues with Memtest86+
Run memtest for at least 8 passes, preferably overnight, per RAM module per slot.
Let us know the results.