biarritz 2 cutting out?

Hi got a biarritz 2 shower that has decided to cut out on me,it runs for approx 5-10 mins then the thermal protection kicks in & it shuts down,no water flow.I've also noticed the solenoid valve is very hot,not quite sure if this is normal,was wondering if solenoid overheating shutting down supply or overheating caused by something else causing solenoid to shut down

gary
July 2010