Microsoft's newest version of Windows contains serious flaws that allow hackers to steal a victim's data files across the internet or implant rogue computer software.
The company has released a free fix for the software which had been billed as the most secure ever.
A Microsoft official acknowledges the risk to consumers is unprecedented.
The glitches allow hackers to seize control of all Windows XP operating system software without requiring a computer user to do anything except connect to the internet.
Microsoft has made a free fix for both home and professional editions of Windows XP on its website and has forcefully urged consumers to install it immediately.
The flaws, discovered five weeks ago by independent security researchers, threatened to undermine widespread adoption of Microsoft's latest Windows software, which many hope will be an economic catalyst for the sagging technology industry.
The company sold more than 7 million copies of Windows XP in the two weeks after it hit stores on October 25th.
The Windows XP problems affect a little-used feature that eventually will allow consumers to control high-tech household appliances using their computers. Called "universal plug and play," the feature is activated by design in every copy of Windows XP and can be added manually to Microsoft's earlier Windows ME software, also used by millions of consumers worldwide.
Microsoft says a new feature of Windows XP, known as "drizzle," can automatically download the free fix, which takes several minutes to download, and prompt consumers to install it. Microsoft is also working with other software companies, such as leading anti-virus and firewall vendors, to build protection into their products.
AP