An Illinois judge has thrown out an appeals court ruling that would have enabled a nationwide class-action lawsuit against Intel over its Pentium 4 processors.

The Illinois Supreme Court reversed the decision of the appeals court, which had said the suit could go forward. The action accused Intel of misrepresenting the speed of Pentium 4 processors.

The case was originally filed by Barbara's Sales and others in 2002. The case reached the Supreme Court after appeals by Intel. The plaintiffs originally sought to apply two California laws and one Illinois law to launch a nationwide suit.

However, as the two states' laws conflict, the suit applies only to Illinois law, Supreme Court Judge Thomas Fitzgerald wrote in his opinion. He ruled that it couldn't go forward as a class action.

Fitzgerald sent the suit back to the appeals court. The case can now proceed as an individual action, with Illinois law governing the issues of liability and damage, the judge wrote.

The Pentium 4 processor was launched in 2000, and the plaintiffs alleged that it didn't live up to the represented advancement in performance over Pentium III or Advanced Micro Devices processors, according to the court document.

Intel is gratified with the outcome and has yet to decide on the next steps to take, said Chuck Mulloy, an Intel spokesman.

Barbara's Sales couldn't be reached for comment.