Microsoft releases an emergency security update to fix a critical flaw present in all supported versions of Windows. The patch comes as virus writers are starting to ramp up attacks that leverage the vulnerability. If you took advantage of the FixIt tool that Microsoft shipped last month to blunt the threat from this flaw, you should take a moment now to undo that fix. You will need to reboot the system before installing the official fix, which is available from Windows Update. After I applied this patch and rebooted the system, Windows Explorer stalled, leaving Windows unresponsive.”]
Source: https://krebsonsecurity.com/2010/08/patch-for-critical-windows-flaw-available/