A new company policy could leave people using pirated copies of Microsoft's Windows vulnerable to viruses. The company says it's going to limit how those running illegal copies of the program get software updates, including security fixes. By the middle of the year, the company will require users to prove their Windows copy is authentic before receiving some software updates. The company says it'll allow those running pirated copies to continue to get security fixes, but only if they sign up to automatically receive security updates. Some security experts fear the change will increase Internet security problems in general. They say computers that are open to virus attacks could in turn attack others. Microsoft thinks the authentication requirement will boost overall security.