My 350 combi will only issue hot water if the CH system is on?

My 15 year old 350 combi has developed a fault in that if the CH is off and you turn a hot tap on, HW comes out but the boiler shuts off within 1 minute. This has to be restarted from the reset switch at the top of the boiler.
Before the system powers off, it is also very noisy at the boiler and sounds like there is boiling within the chamber.