My Kenwood dishwasher KDW24FI/B has

Question

My Kenwood dishwasher KDW24FI/B has worked fine for approx 2 years. But now when I put my dishwasher on, the cycle never seems to end. After a few hours of running I opened the door to find the tablet hadn't dissolved but lots of steam coming out. I tried 2 more times and the same thing happened. The pump is working and everything seems ok. After reading the manual I have noticed the salt and rinse aid lights are iluminated. I have never put salt or rinse aid in since I had the dishwasher so this may be irrelivent. Can you help please?