Microsoft's next Windows operating system, codenamed Longhorn, is being sold on the Malaysian black market a year before it is due to be released.
The software is thought to have come from a very early version of the operating system handed out at Microsoft's Professional Developer Conference in October.
The code is also available for download from the company's website, but only for Microsoft Developer Network subscribers.
"Microsoft is aware of the pirated copies of Longhorn. These are developer codes not fit for business or consumer use, as it is not a complete product," the company said in a statement.
"We are working closely with the Malaysian Ministry of Domestic Trade and Consumer Affairs to ensure that our customers and businesses are protected."
CDs containing the code were spotted in Johor Bahru in southern Malaysia, the closest city to Singapore. They were priced at less than £2.
Microsoft chairman Bill Gates has promised that Longhorn, which is not expected until 2005 at the earliest, will be the biggest launch of the decade for the firm.
The new operating system includes increased security measures and digital rights management software ... to stop piracy.
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