I used to own an X-Board 61 - LOVED that controller.
Is it possible that Windows selectively disabled the device? It is the default behavior for Windows to do so, if a device has been idle for some period of time. This will then make the device unavailable to Sonar, until it is disconnected/reconnected or Windows is restarted.
To check this, and change the Windows default behavior, there are a couple of ways to get at it.
One way is to go to "Control Panel\Hardware and Sound\Power Options\Edit Plan Settings", then click on 'Change advanced power settings'.
Once there, scroll down and expand USB Settings, then expand 'USB Selective Suspend Setting', and set to 'Disabled', click Apply and close your way out of it all.
Once the above is accomplished, you may still have to disconnect the USB cable for the X-Board and connect it back in again.
Then, you can go into Device Manager and you should see the device listed in the Sound video and game controllers, if you expand that.
Bob Bone