What is wrong with my ADP 4403 Whirlpool dishwasher?

My dishwasher (whirlpool ADP 4403) has been working fine for around 3 years and recently it seems to stick mid-cycle. I use the same cycle which is the eco-normal 50 degree one, it starts fine and makes the usual sounds. In the past it takes around 2 hours to complete a cycle but now it stops after around 50 mins and the small green light near to the start button flashes continuously. When I press the start button the dishwasher makes a sound similar to that when it is drying for about 2 mins and then it appears to have finished. When I open the dishwasher things are not fully clean and there are white streaks inside the machine. Also, things do not seem fully dry. I have tried filling up the salt, rinse aid, cleaning the filters and running it through with dishwasher cleaner but nothing has improved it. I would like to know whether this problem can be fixed, or if I need to think about getting a new machine. Thanks.