…is an error I got trying to perform a copy command. It went away, but, it's the same error I was getting during my recent struggles with checksum errors.
There's not much more info to provide… it was one of the 'range' keys on the Copy. I don't see this error listed in the book, on this forum, nor does its wording make much sense.
My (uninspired) guess is that the system thinks that you are trying to press and hold a key to modulate it. It may be that you actually are holding the key for a long time, or that it mistakenly thinks you are.