My system is having MSI Z77A-GD65 mobo, actually I have bought this new motherboard as my previous board had turned out faulty. The problem that I am facing with the same is that when any storage device is attached to the USB 2.0 ports then the system hangs at post and gives me a b4 code. When I am not having anything attached to the usb ports then the system hangs generally as well. The system starts fine for the first boot but it does not boot properly after that. I am not able to make out if this issue is with the motherboard or usb?? Is there anyone who has faced the same and has an idea about it and can help me solving it out as well?