Appcrash on pretty much everything

Hi everyone, not sure if this is the right section on the forum to ask this but I'll ask anyway.

I built my new gaming rig last week and since I switched over, pretty much 99% of my apps are crashing. Here's my computer specs :

MOBO : Asus P8Z77 V-Pro
CPU : Intel i5 3570K
DDR: 8g Kingston HyperX 1600mhz
Video Card : MSI GTX 660 Ti
SSD : OCZ Vertex 4 128g
PSU : Corsair AX860

I installed Windows 7 Ultimate on it and everything kept crashing, so I reinstalled another version of it , still happening. I tried installing another version Windows 7 Professional , updated everything including SP1 and problem still occurs. When playing games like World of Warcraft I'll get the error #132, playing Starcraft 2 the game will simply crash with a pop-up telling me to send the error to blizz and re-open the game bla bla bla , while playing Dota the program will simply stop responding.

I did a complete 8 hours memtest and everything was fine. Tried with 2 other memory stick from my old computer and the problem still occurs. I have the latest nvidia drivers and everything.

Something odd about this is : random apps like sharepod will crash right at the start, and even when trying to do the windows experience score (you know the thing that rates your specs from 1 to 7.8) it will crash midway through the test.

Any idea what could be the root of all those problem ? Could it be the CPU that's defect ?

Thanks for any advice !