The latest RC2 has signatures with extended validation certificate (co-signed by Microsoft).Maybe you're not affected by this because you didn't reinstall/reset/refresh Windows lately.
I think my problem is similar with HMP.A. My OS wants signed drivers, so if I install HMP.A with its unsigned drivers, I may end up with problems like BSOD. That's why erik loman includes a note about the status of the signature of the beta that is released.
Program Compatibility Assistant Service doesn't like some drivers. I don't know why. You have to check if it is running in services.msc or Task Manager services tab.