GypsumFantastic:
These are digital inputs, yeah?That's quite a long cable run but should be ok if you get the circuit right. I don't think you should need special cables etc.
What pull-up / pull down resistors are you using?
From the sounds of everything here, I'm believing it is an electrical noise issue. I'm considering changing the wire runs to Cat 6. To answer your question, I'm using 1/2 watt, 2.2k resistors for each button(not sure if it matters but the resistors are mounted closer to the arduino rather than the button end). Yes i'm using the digital inputs