I have an older GE Dishwasher (PotScrubber 900) that started this problem a few weeks ago.
I can load up the dishes and start the wash cycle. Once started if for some reason you have to open the door, which stops the machine, when you close the door and re-latch it simply will not start up again. All you hear is a hum sound from the motor. If I let it set for a while then you can restart it.
I've also noticed on a few occasions where just trying to use it after a few days it also will not start ... just the hum sound. I turn it off/on a few times then let it set (1 or 2 hours) and the it will start the cycle and finish.
Any help will be appreciated.