People who had problems voting were using older versions of Netscape Navigator infested with Y2K-related bugs, causing the browsers to crash, election officials said. Others couldn't execute their votes because the lines were tied up.
"We had to work around the clock to circumvent these problems," said Joe Mohen, chief executive of Election.com, the company that made the online election possible for Arizona's primary. "We tried to think of every conceivable problem, but we didn't expect that so many people would have very old versions of Netscape."
The event should go more smoothly for the remainder of early voting this week, officials said. The regular primary election is March 11.
Despite the problems, about 14,000 Arizona Democrats voted yesterday. That's more than in the entire 1996 primary.
"This is the first time Internet voting has been done in history, and we certainly expected some glitches," Mohen said. "Overall it was a very good day."
The results could be a major score for the Internet-voting movement. Many industry experts claim the Web will revolutionize democracy as more people are attracted to the ease of registering and voting online.
But Arizona's experiment has not gone without controversy.
Justice officials and several private organizations worried that the push for Net voting would disenfranchise poor and minority groups that frequently don't have access to computers. Equally troublesome were potential security issues.
To allay those fears, party officials have promised to put up 29 more polling booths in low-income neighborhoods on election day.
And to address security concerns, a team of experts has been on hand at the Democratic Party's computer center, ready to fend off attacks.
Election.com, based in Garden City, N.Y., also offers online voter registration software.