Flooding on Indesit IDL705?

The dishwasher floods during certain washes, and then doesn't flood for quite some time. The second and last lights however flash at the end of each wash (indicating that something is wrong). I can't work out what is causing the flooding as it's doesn't seem to be anything to do with the packing of the dishwasher. We have tried to add additional sealing at the bottom of the door, but this still hasn't solved the problem.