It's been eight years since the disaster of the deadlocked 2000 presidential election, which ended up before the Supreme Court. And it's been six years since Congress tried to prevent a repeat by passing the Help America Vote Act.

But election experts across the country say that, despite $3 billion in federal spending to solve the problems, they still expect Nov. 4 to bring any number of headaches, from long lines to equipment malfunctions.

The Post's Mary Pat Flaherty reports that the huge turnout expected could strain election operations, which have been in a constant state of flux as jurisdictions have introduced new machines and procedures in recent years.

Touchscreen machines have fallen into disfavor, and now more than half of the nation's voters will cast a paper ballot that will be read by an optical scanner. That creates a paper trail, which can act as a back-up if there are questions about the final tally.

Millions of voters, many of them in battleground states, will be using machines that are different from those used four years ago. Also, a series of recent legislative debates and court rulings could leave poll workers confused about what identification is required of voters.

In 31 states, this will be the first presidential election using new statewide registration databases. When voters arrive at the polls, their information must match that list, which could lead to problems in places where the rules on what constitutes a match are particularly rigid.

"The voting process is going to be tested in a way it has not been in recent history," said Tova Wang, president for research at Common Cause, a government watchdog group.