Texas Instruments TravelMate 5000 Series User Reference Manual page 191

Using the AC Adapter
5.
Note: The computer must be completely powered off when
n
connecting other external devices. You cannot use Fn-F4
or Suspend.
9-26 TravelMate Options
If you plan to use other external devices with your unit,
connect the device to the computer before setting the
computer power switch to the on (|) position.