A colleague sent me a link to an interesting article that looks just like an integer overflow issue:

http://www.palmbeachpost.com/politics/content/news/epaper/2004/11/05/a29a_BROWVOTE_1105.html

Broward machines count backward
By Eliot Kleinberg

Palm Beach Post Staff Writer

Friday, November 05, 2004

FORT LAUDERDALE — It had to happen. Things were just going too smoothly.

Early Thursday, as Broward County elections officials wrapped up after a long day of canvassing votes, something unusual caught their eye. Tallies should go up as more votes are counted. That's simple math. But in some races, the numbers had gone . . . down.
 
Officials found the software used in Broward can handle only 32,000 votes per precinct. After that, the system starts counting backward.

Methinks the software used 16-bit signed ints!