It is possible that the water pressure drops (someone has used a tap in the house, flushed the toilet). This drop makes the shower stop.
Alternativle you may need to re prime the shower. Take the cover off and you will see a blue lever like button. Make sure shower head is on the floor of the shower and press this button down. This will flow the water through the heating element freely from the cold water feed hence re priming the heating element. Go to Miras website and you can download the manual for the shower and read in the comissioning section about how to do this properly.
Andy G
January 2007