3 Program lights flshing and beeping?

When I start the dishwasher it seems to work and then after about five minutes I hear a beep and it stops. When I open the machine the first three program lights (of five) are all flashing and the machine has stopped. The beep stops then starts again so i have had to switch the machine off. I have cleaned out all the filter as I thought there may have been a blockage. It seems as though the dishwasher possibly didn't empty previously?? Any ideas before I have to ring an engineer?