Here is one case when flawed ballot data on a paperless electronic voting machine caused a serious election miscount. It was detected only because voters also used optical scan paper ballots in the election.

Mrs. Hawkins-Curtis, a candidate for Rowlett mayor was added to the ballot four days before the start of early voting. The change in the ballot definition wasn't programmed into all 390 ES&S iVotronic machines until after early voting began. The ballot data was changed only in Rowlett polling places.

When the results were combined with the results from ES&S optical scan machines, the error caused the tally software to improperly tally results in the mayor's race as well as 17 other races, including propositions and school board races. Nearly 5,000 of the 18,000 ballots were improperly counted.

A few minutes later, a second count - called the reconciliation process - began to show that the number of voters who signed in at numerous precincts didn't match the vote totals, Ms. Pippins-Poole [county's assistant elections administrator] said.

The extent of the miscount wasn't discovered until Monday when Election Systems & Software began a thorough investigation, Ms. Pippins-Poole said.

...The touch-screen ballots have been used in early voting in 91 elections since 1998 without any problems, Ms. Pippins-Poole said.