Responding to consumer complaints that the screen on the recently introduced iPod cracks too easily, Apple said on Wednesday it will replace any defective units. Apple introduced the nano with great fanfare three weeks ago and chief executive Steve Jobs expects it to become the best selling iPod. The nano replaced the iPod mini, which had been the best-selling iPod model.

The problem has occurred in less than one-tenth of 1 percent of the iPod nanos sold so far.

Apple's spoksman said that any user with a defective screen should contact Apple and the devide will be replaced frre of charge.

In its most recent quarter, Apple sold 6.2 million iPods and accounted for about a third -- $1.1 billion -- of the company's overall revenue in the period.

Apple introduced the iPod nano in two versions: a two- gigabyte model selling for $199 and a four-gigabyte model for $249.