This seems to be a common problem. Mine does exactly the same. It will work but is "Russian roulette" as to which programme is selected. If you have found the solution please let me know. I am thinking of changing the Timer Board £64.99 But not sure if this is the cure.
http://www.buyspares.co.uk/dishwasher/belling/idw604-444445898/catalogue.pl?path=67231:400588,297877:297772&model_ref=440857
Mags, August 2010