random readings on switch

I have a circuit connected to a mini pro input. It provides a 5vdc (HIGH) supply when the circuit is operational and 'nothing' (LOW) when the circuit has finished its operation. The 'nothing' does have a bit of floating voltage - about 0.04 volts (at least on my meter). This seems to be enough to give an occasional false reading at the pin. There is a 220 ohm resistor between the circuit and the input as well as a 10k to ground pull down resistor.

Does anyone have a suggestion on how I could either adjust the hardware (putting in some sort of filter to eliminate the floating voltage) or adjust the software (only reading inputs about 2 or 3volts?)

Thanks ::)

hardware you can add a capacitor into the mix http://www.ikalogic.com/debouncing.php

software you can detect when the pin changes (button pressed) then wait a couple milliseconds and see if its still down http://www.arduino.cc/en/Tutorial/Debounce

You need to have the pull down resistor on the input pin 10K should have been enough but drop it to 4K7 and see if it improves.