The problem was that the officials would run a "current total" of votes to see where the candidates stood in the votes that had been counted so far. They did this every hour or so to monitor the results. And the totals kept getting bigger and bigger. Turned out the software was supposed to report:
currentTotal = sum( precinctVotes )
but instead reported:
currentTotal = sum( precinctVotes ) + currentTotal
Count the same votes over and over and the totals just mount up. No real damage was done, since they had the real precinct results to go to. Presumably a coder at Hart InterCivic has already changed that routine to reinitialize variables as needed.
What bothers me about this is that it's such a blatant bug that any real full up test--such as a dress rehearsal of an election--should've caught it. So the county is just accepting delivery and using the stuff in blind faith. Meanwhile the vendor has demonstrated that they don't deserve any trust if they're letting stuff like that through.
Can I have a paper ballot next time?