GT520 crashes on youtube

hey

I have a problem with my PC and I'm pretty sure it comes from the Graphic Card. The problem is that when I open some certain softwares, the computer crashes and the only way to get rid of it is to hold the power button for some seconds, until the PC is turned off.
For example when I try to watch a video on YouTube, the computer crashes in less than 5 seconds. Or when I use Autoacad 2013, it crashes in less than 10 minutes. I reinstalled my windows but the problem remains intact. I installed the drivers both from CD and from Website, but the problem remains the same.Today I uninstalled the NVIDIA drivers and allowed the windows to install the standard driver and with that driver I could watch youtube videos with no problem. So I assume my graphic card is OK but the drivers are not.
Also when I try to rate my computer, the computer crashes and the rating doesn't complete.(but with the windows standard driver it could complete and it was 1 for both Graphics and Gaming graphics)
IS there anyway I could get rid of this problem and use my PC comfortably until GTX660Ti is available on market?  

P.S. Before installing GT520 I used an old PCI express1 graphic card and I didn't have any problem with YouTube or system rating.

Here are the specifications of my PC:
Main Board: Gigabyte X79-UD3
CPU: intel core i7 3820 3.6 GHz
RAM: 16 GB DDR3 Kingston hyper
Graphic Card: Geforce GT 520 1GB (PCI express)
Power: corsair gs700
Monitor: Dell U2412M
Hard drive: 128 GB Samsung SSD
Operating system: windows 7 enterprise 64 bit


Thank you very much in advance