USB drive problem accessing database due to port shut down

When I have my USB drive connected to my router, no problem. When instead I have it connected directly to my PC (a laptop) (resulting in the same drive letter assigned to the drive as when connected to the router), the PC doesn't stay connected to the drive, such that after awhile I lose connection to database programs (with resulting errors on attempting to access them) and run the risk of corrupting them because the files didn't get closed properly. (Database progs = Outlook and Clipmate.) It would appear that perhaps some power management on the PC is trying to conserve energy by shutting down the USB port when not in use, but I checked them in Device Manager, and it is not set for power saving to shut them down. What could be causing the shutting down/interruption of the USB ports after a period of time?

1) Just to verify: when you say you checked Device Manager, that means you checked Power Mgt settings on the Root hub for ALL the USB controllers listed in DevMgr?

2) What make/model drive are you using? Is it a self-powered or bus powered device? (ie does it have its own AC cord)

3) Have you tried a different drive to see if you get the same result?

4) Is the laptop plugged in or no when problem typically occurs. Does it happen while laptop is plugged in?