I've an intermittent problem where on occasion when I try and start the bus nothing happens , to "cure " it I take the gear selector out of park into one of the other positions then back into park and the bus will start as normal .
I don't mind doing this but I'm afraid that some day the bus just won't start and I'm stuck in the middle of nowhere .......and of course I'm late

Has anyone an idea as to what might be causing this ?

Thanks in advance
Brian