My wife’s computer was stuck in a Windows boot loop. We’d get the Windows 7 boot screen, and it would display a single pixel of the Windows 7 logo, then reboot itself endlessly. Booting in safe mode made it fail on classpnp.sys.
Any number of things can cause this, and it usually happens after you swap a motherboard. Enabling AHCI turned out to be the fix. Enabling AHCI also can be easier said than done, but I figured it out. She’s running Windows 7 (for now) but these same tricks should also work for Windows 10.

David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.





