Solved
I have been using a Laboratory grade power supply with constant voltage at 3.3V.
After some 4 days of messing around and frustration I decided to put a 22uF electrolytic cap and a 0.2uF Tantalanium cap across the supply and straight away I had no problems.
I hadn't bothered with these before as it was a Laboratory grade supply.
Oh well live and learn
Cheers and thanks to all
Paul