I think this same problem came up on this Forum a few months ago. I cannot remember if a solution was found.

However, when my original KN7 behaved like that, I was advised to replace all the leads with new ones and using a 'Surge' Plug make sure only the KN7 was connected direct to the mains socket because it is never a good policy for the mains power lead of a keyboard to share a socket with other devices. It cured the problem for me, thank goodness.

Just a thought!

Audrey