Don't want to throw a simple one in, but you haven't got "loop" lit at the bottom left have you? If that is lit or selevted then it just keeps going round and round as you said, 1 to 30 back to 1 up to 30 and so on until you switch it off. It's probably not this and no offence was intended but sometimes it's the simplest little thing that causes problems :) Happy days and long life!

Injustice will be avenged.
Cofiwch Dryweryn.