1) Does it do it every load?
2) Unplug the unit and remove the two screws at the bottom of the front panel. Pull out on the bottom of the panel until it releases the top of it. Look at where the transmission goes through the tub. Do you see water tracks?
Can you remove the two 3/8" screws securing the top. They are just inside the front. You will have to remove the bleach tub if you have a bleach dispenser. Hold on to the lid and lift the top up by the front. A peice of duct tape helps to hold the lid in place. Find the fill hose on the top of the tub and follow it back to the white plastic. Do you see water tracks here?
You can try drain cleaner or buy a small pipe snake from home depot. If you have an older house you may want to call a rooter service. Also check you basement if you have one. See if any water is backing up through the floor drain. If you need to get by another day test the pump out on a gentle cycle. (it pumps it out slower)