Yes, protect.dll is heavily protected with Starforce virtual machine but... what's interesting... some game exe/dll files can be protected with virtual machine too, making it really hard to crack. That's why it's wiser to find a generic hole.
Of course, as you said, protect.dll itself is not a driver, but takes hardocore usage of them
. It's the place responisble for the critical task:
the CD check.
Regards.