I do not know exactly what the classpnp.sys does, but the pnp part looks like plug and play, which could be related to a device driver that is not behaving.
I will keep doing research.
One more thing, just knowing a device driver loaded may not be enough. I always like to install those separately so the time is distinctive. If you go through the process from Microsoft, they mention the time installed could be important to help finding the right one. Also, you might even write down a device driver update so you would know which one was probably involved.
Woops, another one more thing. If you are going to replace the hard drive anyway, you basically have a license to steal and try just about anything you want. Maybe using the F12 key during boot would allow you to reinstall now. Remember the F keys may be set up differently. You may or may not have to use a function key with the key or enable the F keys somehow. Next time you boot, try just hitting the space bar continuously during boot.