"The Windows Root Certificate Program enables trusted root certificates to be distributed automatically in Windows. Usually, a client computer polls root certificate updates one time a week. After you apply this update, the client computer can receive urgent root certificate updates within 24 hours."
"this update is causing additional problem on computers that are running Windows 7 Service Pack 1 (SP1) and Windows Server 2008 R2 SP1. This includes the inability to install future updates. The KB 3004394 update does not cause any known problems on the other systems for which it is released. We recommend that you install the update on the other systems."
An update is now available to remove the Microsoft update KB3004394 from Windows 7 SP1-based and Windows Server 2008 R2 SP1-based computers which you can find here KB3024777;