Thank you once again. It is odd that Iliaspap here disabled Legacy support of USB USB mass storage and it seemed to fix his problem. I have 3 pendrives that I've booted on other machines but none of them work consistently with this motherboard. I will see shortly if my new USB 3.0 pendrive will work when it arrives.
After 3 days, my system is rock stable, no problems anymore, I have my usb 2.0 WD connected on the back usb ports, tested both usb2 and usb3 ports, same resaults. Also I didnt disabled USB Legacy support, I disabled only the USB mass Storage Fuction. And to be certain, I just tested to re-enable usb mass storage function, I had the same issues again, Slow Bios Post and Took ages to load windows7 x64. So It is 100% the solution of my problem.
Tnx for the help guys. Greetings.