Unstable PIC output - Pins sensitive on touch

Hi,

I have a simple LED flasher programmed on a PIC16F877A, but the output of the pin (RC4) is always high unless I say put my finger on any one of the other pins, then the LED flashes as expected.

I presume this is capacitance related but what is happening and how can I rectify it ?

The circuit is extremely simple, two 15pF caps on a 4Mhz crystal, an LED and 1k resistor on an output pin RC4.

Thanks !

Nevermind, /MCLR had no pullup resistor... durr :)

Well it seems now its working but whenever i wave my fingers/hand close to the micro (touch some pins or even touch the DIP casing) it still goes wierd and keeps the LED on ! If I do this enough the PIC seems to stop completely and only re-programming it will fix it.

This doesnt happen when I ground or vdd myself... what on earth is going on ?

Ok I solved the problem by disable low voltage programming in the config... seems to play havoc with the thing !

Have you made all the unused pins outputs or tied them high?