It is a hardware problem, not software. If there is any chance of fixing it softwarewise, it would be in firmware updates for the printers; though even that is iffy.
Networking the printers would definitely solve the problem as they would no longer be flooded with spurious data overnight and there is no reason why they couldn't still be only available to one user. Set them to a static ip, change the port on the desired user to that ip, and, poof, you're done.