If you have not done so yet...
Article ID: 3025419 - Last Review: 01/06/2015 20:09:00 - Revision: 9.0
Microsoft System Center 2012 Configuration Manager / Service Pack 1 / R2
Microsoft System Center Configuration Manager 2007 / R2 / R3 / Service Pack 1 / Service Pack 2
According to the support KB it mentions there is a newer driver signing method.
This will also mean you may need to reimport the drivers you currently have imported.
Hope this answers all the questions.