Right I forgot to be specific about the my PC spec, here :
OS : Windows 7 Ultimate 64-bit
RAM : 16GB
Processor : Intel i7
GPU : GTX Titan Black 4gb
Also I have sent ticket to Gearbox support. They have replied, but they say since it's holiday, the technical support won't reply anytime soon. I only given the link to search about my issues.
Nope, I didn't use controller. Just keyboard and mouse.