Baxi 108e failure?

- I accidently asked this question as an answer. Here it is again.

-My central heating is working OK.
-If I just require Hot water, The boiler lights-up and the upper red neon indicate temp is building, then they all suddenly start flashing insanely (all red neons), then go off - no hot water.
- This happens with increasing frequency (i.e. not all of the time)

what is wrong, the boiler is 4 years old and just out of guarantee! Has the obsolesce chip just kicked in?