I've had this one a couple of times - most recently when rolling out another set of software updates.

Microsoft detail what these codes mean on their website at: http://www.microsoft.com/downloads/details.aspx?familyid=9F009942-B4D8-4A70-8F74-E81CCC7B2309.

Simply put, SMS needs you to run the Security Update scanner before it will install the software update. I haven't had a problem with the expedited variant and I think that makes most sense in the circumstance.

And a quick plea for help: has anyone got any experience with EdTools Steadfast or similar and SMS?