Yes, don't target the Windows drivers, sometimes BSODs don't always give us the real driver which is causing the problems, and therefore it blames a Windows driver instead; Driver Verifier will help cause another BSOD which should hopefully display a real cause.
For the driver explanations, fltmgr.sys is related to the file system (see
fltmgr.sys also) and Npfs.sys is another Windows driver which I'm not able to find much information about.
You can read the Stop Code links, as they have a list of usual causes, which you could also try and test.