Did you try midi reset first ?
Did you check to make sure you novation was still listed in devices ?
Have you turned off sleep for usb devices in the power option if on windows ?
Yes, I’ve checked into all those things - it’s sporadic, and the keyboard continues to work as expected - only the faders, knobs and transport controls go away. Sigh.
What is your operating system and which version of the Novation USB driver have you installed?
Are you connected to a hub at all? If so please remove this and connect the Impulse directly to a dedicated port using the supplied cable. Eventually try another cable and or port.
Do you use any further devices or software? Make sure to remove/ close all these and use only the minimum required to operate with your Impulse.
Please let me know, if I can be of any further assistance to you.