Did you turn the ScanSnap off and turn it back on?
Close the ADF paper chute (cover) to turn off the ScanSnap, and then open the ADF paper chute (cover) to turn it back on.
Make sure that you leave at least 5 seconds between turning it off and on.
TIP
When the startup mode of the ScanSnap is set to [Fast], the ScanSnap is not turned off even if you close the ADF paper chute (cover).
Unplug the power cable from the AC outlet and plug it back in again, and then open the ADF paper chute (cover).
If the problem still persists, contact the distributor/dealer where you purchased this product.