Emergency Patch for Windows

For years, Microsoft has released its patches on a predetermined day -- the second Tuesday of every month -- but it has occasionally released patches ahead of schedule when bugs have been actively exploited by computer criminals.

The last such emergency patch issued by Microsoft was in April 2007, when the company fixed a bug in the way Windows processes .ani animated cursor files. That flaw was publicly known and being exploited in attack code hosted on hundreds of Web sites.

Microsoft is expected to release the update around 4:00 p.m. ET. The company also will release more details about the patch in a special Webcast. I'll have more information on this update as soon as the patch is out and details are released. Stay tuned.