Windows update users and prudent sys admins might have installed the latest Windows patch without a thought. That might not have been such a good idea. The patch is meant to fix a hole in Windows Messaging but can end up causing a severe performance degradation. If you have Windows Update running on automatic and you're experiencing a nasty slowdown on your system, you might want to try removing patch 811493. Users with the performance problems report that removing the patch fixes things. The patch fixes a relatively minor security problem where an attacker would have to have physical access to the machine.