After you install the Convenience rollup update for Windows 7 SP1 and Windows Server 2008 R2 SP1 (3125574) and the System Center Configuration Manager client, the Software Metering Agent fails, and the following error message is recorded in the mtrmgr.log file:
Software Metering failed to start PrepDriver
This error can occur if you install rollup 3125574 before you install the System Center Configuration Manager client software. In that scenario, PrepDrv is not installed during the System Center Configuration Manager client setup process.
For a couple options on how to resolve this issue, please see the following:
J.C. Hornbeck, Solution Asset PM
Microsoft Enterprise Cloud Group