Apple is investigating a design fault in the new 15-inch PowerBook G4 that apparently causes white spots to appear on its screen.

Apple has issued the following statement: "The new 15-inch PowerBook has been a big hit with customers since its introduction last month. However, some customers are reporting the appearance of faint white spots on their displays after using the system for a short period of time, and Apple is investigating these reports right now. Any customers experiencing this problem should contact AppleCare."

According to postings on Apple's online user forum, many PowerBook owners have experienced the problem.

One PowerBook owner says: "On my PowerBook screen there seems to be a spot where things appear brighter than the rest of the screen. It is about one-inch in diameter. It almost looks like the white spots that occur when you push on the back of the screen. The computer is brand new, and it has had the spot since I bought it."

When Apple introduced the aluminum version of the 15-inch PowerBook in September, Steve Jobs said the device: "Sets the bar for professional notebooks even higher."