Thanks for the input. I have followed and something very strange is happening :

I am using an external oscillator 4MHz. My program simply toggles one pin every 30ms.
Problem is that I see sometimes the toggling if I touch the PIC,leg of the capacitor (earth) or touch the bench the circuit is left on and sometimes it works fine and sometimes the led is just on constantly.

I have never ever seen this happening with any PIC I have used till now. What could be the reason for this??? Any advise ????