There has been an error on the pcb. Try holding reset down for a couple of seconds and see if that fixes it. If not turn it off for about 5 seconds and then back on. If that doesn't fix it you may need a new pcb which will probably set you back £150 + fitting.
dckidd
December 2008
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix home heating systems.