Hi Carol,
I had the same problem this weekend, I found that the problem was probably caused by the anti-flood switch.
At the bottom of the dishwasher is a plastic cover, remove this (after switching of at the mains) have a look in the bottom of the machine, if it is filled with water simply mop it out and this should solve the problem, it did for me. If you press the programme button for 5 secs, it seems to reset itself.
Alun James, September 2005