He said the machines aren't suffering from a universal software glitch; rather, some individual devices have unique problems. These were addressed by recalibrating the devices, a process that didn't involve the loss of any votes. "Like anything else, we'll shake it out as a minor problem," said Corwin.

Florida isn't alone in encountering such glitches. In Texas, there have also been complaints about flipping in some systems. One Collin County voter even blogged about it. However, a spokeswoman for Texas Secretary of State Roger Williams said the office had been in touch with counties where the vote-flipping allegations occurred.

The election judges in those counties have assured Williams' office that there isn't a problem with the machines, she explained. It may be a fingernail or some other user error involving the voter hitting a button without realizing it. "However, this only serves to emphasize the importance of the summary screens, where a voter can make sure the correct ballots are cast," the spokeswoman said.

Despite official reassurances, the incidents set off alarm bells for a couple of e-voting critics. "You can only imagine what Election Day will be like if these problems were encountered with a relatively small number of voters at the polls," Avi Rubin, a professor of voting technology at Johns Hopkins University and a Maryland elections judge, said on his blog.

"While most of my comments about e-voting have to do with security threats that are invisible, I am also discouraged by the widespread technical problems that are not just noticeable, but screaming for attention," he wrote.