During an investigation into the malfunctions of the voting machines in the 2004 general election, the machine being used for a demonstration froze and failed.*

"It's worked fine up to this point," Gerbel said, faintly flustered, fiddling with wires.

Minutes later, the UniLect system was back online, tabulating mock votes correctly, working just the way it's supposed to.

That brief episode, more than any other during yesterday's demonstration before state officials, illustrated how the computerized system can be mostly reliable, yet prone to occasional glitches that can temporarily confound even the people who know the system inside and out.

UniLect designed the touch screen systems that are at the heart of an election investigation in Mercer County, where some of the machines malfunctioned because of a computer code that was installed incorrectly.