Online retailer Amazon.com 'accidentally' leaked expected pricing for Microsoft's Windows XP software yesterday.
Prices were put up on the site last night but were pulled soon after.
Microsoft today remained adamant it had not yet set specific prices for its Window's XP operating system, due for release on 25 October.
"We are not sure how this has happened," said a spokesperson. "We will make an official statement on prices once the have been agreed."
But red-faced Microsoft also faced rumours over the rollout of its anxiously awaited software amid reports that some of its beta testers had not yet received their preview copies of XP - and were not likely to until the end of the month.
Microsoft refused to comment and would not confirm how many testers were affected.
According to Amazon's short-lived advert people can expect to pay $299.99 (£210) for XP Professional, $199.99 (£140) for the professional upgrade and XP Home, and $99.99 (£70) for XP Home upgrade.
Amazon was unavailable for comment.