Addionally, please check your USB connection:
When using a USB keyboard on a system with multiple USB controllers, we recommend that you designate one of them exclusively for the keyboard (and possibly the mouse) and keep other devices connected to the other controller(s). This is often an option on desktop systems, where additional USB controllers can be plugged in as PCIe cards. In this case, the designated controller for input devices should remain in dom0 but be limited to input devices only.