I pulled mine out to see if I could jog my memory. The floating issue rings a bell but I seem to remember the TI chips had built-in pulldown resistors. I think I found actual TI chips, was it a problem with the clones perhaps? Are there other variables in the circuitry that would make this not work for some people but work for others?
The project definitely gave me an appreciation for electronics and how much is hidden under that abstraction level. I really wish I'd kept a journal or blog while doing mine!