Strangely behaving 16F877a

[financecatalyst]

My first impulse would be stray capacitance. Pins should be pulled high or to ground with resistors and never left floating.

You mean all the remaining 36 Pins? If you do then please can you also advise me suitable values.
Thanks

[comwarrior]

any resister from 1K to 100K... anything to pull the pin to ground...
You could just wire them straight to ground, but you need to remember to set all the pins to input...

[financecatalyst]

thanks for the input to all. The problem was that my MCLR pin was not made high and was left floating. Its working now.