Baxi 80e - combi boiler fault

Hi, I have a Baxi 80e gas powered combi system installed in my house. I'm not sure when the problem started to occur as we moved into the house during the summer - it seemed to be working fine. This problem has only been occuring during the autumn and winter seasons.
Problem
When we turn the heating on it starts up as normal, but then the neon gas light starts flashing after about 10 seconds (with no rhythm). Eventually the heating turns itself off and the 'Pilot' neon light starts flashing to indicate an error associated with the pilot flame. Funny thing is that the hot water function is not affected by this problem, and, if i turn the heating on and fill the sink to do the washing up straight away, the heating system seems to work fine when it switches back over from the hot water.
Fix attempts
I've tried changing the pressure switch (simple task) - as i saw the somebody had mentioned it on another forum. This made no difference.

Another concern is that there are dead bees, wasps, spider etc inside the boiler unit (they must have come in thorough the flue and been baked). Will try to get up there to check the flue for blockages at some point soon. Has anyone had the same problem and implemented a fix that doesnt require me to pay my whole xmas funds to a Corgi chap??

Thanks for reading

Mark[/b]

I forgot to mention, my CH does not have a thermostat.

Hello again. My trek to repair my Baxi 80e has taken a new turn. I've read in another forum that my boiler contains the model 248074 PCB. Baxi have released a new PCB (model 5112380) which is an upgrade of the old model (me thinks Baxi have found faults in the older model). I've recently ordered the new model PCB from ebay (I payed £40 - they're £80 in the parts shops). It seems like a pretty simple job to replace the PCB (I'm very competent with electronics) - the only advise i'd give to others who arent as competent is: make sure you turn off the power to the boiler. ensure that there is no power coming into the circuit before you open it up (turn it off at your house's fuse box).
I'll keep you informed when i try the new PCB as to the results. I'm confident that this will resolve the fault.

Thanks for reading

Mark

Booo, back to square 1 !!

Sadly ( ) the new PCB didn't solve the problem. Anyone else got any ideas what could be causing the CH to be failing? Bare in mind that the HW works fine, and the CH only works if i leave the hot tap running for 5 mins, then turn the tap off.