Baxi Solo 3PFL 60 is driving me nuts!?

My boiler continuously clicks on and off, probably around 3 or 4 times a minute and the combustion flame bursts loudly into life every time it ignites. The thing is it only does this during the winter months when my central heating is on, as when heating the water it is OK and operates normally.

It also plays havoc with my freeview TV reception, in that my picture breaks up and cannot be watcged until my boiler is switched off!

I have had my air pressure switch replaced recently, however to no avail!

Any thoughts would be much appreciated?