WD My Book hangs my PC on boot up

I suspect its because there is some incompatibility issue between the usb3.0 interface of this drive and plugging it into a usb 2.0 output port of the PC which was advertised in the drive that its usb2.0 100% compatible. Coz as i have mentioned, i also have another usb2.0 ext HDD and i didnt have these issues on it. I wonder if someone from WD can 100% guarantee this compatibility.