PIC 16f877a

[CipiCips]

Hmm

so I should put all my pins (register E,C ect.) that I am not using to OUTPUT

[Archangel]

Hmm

so I should put all my pins (register E,C ect.) that I am not using to OUTPUT

Setting them to low outputs gives them a low impedance potential. As inputs with a high impedance potential they are subject to "Stray capacitance" electric fields which typically have relatively high voltage and very low current available. If you need them as inputs, you would either enable weak pullups, tie them to either ground or VDD with resistors depending on your need, again lowering their input impedance to several hundred to a few thousand ohms, exception: If you WANT to use them as capacitor plates, maybe a touch sensor.
You might find some value here:
http://www.electronic-engineering.ch...box_keypad.pdf
http://www.electronic-engineering.ch...g/box_dbg.html

I like how they use a comparator to trigger an interrupt to check the keyboard register.