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Microsoft says it cannot allay the concerns of security software makers over its next operating system, Vista, until it issues an update to Vista. Microsoft is not providing a timetable for that update. The first version of Vista is schedule to be sent to corporate users next month, and sold to the public in January. Security companies including Symantec and McAfee say they need access to the core, or "kernel," of Windows Vista to protect customers fully, but Microsoft is not allowing it. Microsoft has put up a wall called "PatchGuard" to protect the operating system from hackers. Security software firms say that keeps them out, too.

Microsoft last week promised the European Commission that it would change the Vista operating system to meet concerns of security software makers.

Microsoft security expert Kristin Johnsen says Vista will be safer than previous versions of Windows, even with the current dispute.