Potterton Boiler problem

Our Potterton Boiler is around 9 years old, recently it has developed a fault. It fires up ok, runs until the water in the Boiler gets to the correct temp, shuts itself down, pump still running as normal, then wont fire back up again, re-setting it results in the boiler igniting for around 10 secs, then closes down again, result is no hot water, or heating. Thought there might be a problem with the motorised valves, I have two, set them to manual, same result. Any ideas what could be causing this problem.

Thanks

Boiler is??

Thermostat, pump not pumping, blockage, Air flow problems...

Boiler is a Potterton Suprima

Add possible pcb failure to the list then.
You need to see if it's getting really hot and where, is it entirely consistent, does the boiler thermostat knob make a difference etc.