Brother ADS-2000 discoects overnight

We have a Brother ADS-2000 scaer that discoects every night. The sleep settings on the machine are set to the max timeout, and USB power management is disabled, so Windows shouldn't shut off the root hubs to save power. However, the user is still reporting that the scaer shows as discoected every moing.

Suggestions? We've tried updating TWAIN drivers, device drivers, device firmware, etc.