Touch-screen machines can occasionally fail or register votes for unintended candidates. Optical-scan systems can have trouble reading paper ballots that are too long or marked with the wrong ink. At least one study suggests that electronic voting machines can be easily hacked.
TVNL Comment: This has been known since the Bush administration stole the 2000 election. How do the people of this nation allow their leaders to get away with this? This is the kind of things that cause revolutions!