Unable to connect my BBB/

I tried connecting my BBB via usb to my netbook with windows 8.1.
The PWR diode is on,
The USR0 blinks,
and The USR2 blinks really fast or the light is very weak.
My computer don’t detect the BBB. I instaled the driver (bone_drv.exe) manually and still nothing.
Then i tried connecting to a PC with windows 7 and same thing happened.

Any suggestions would be most welcome.