Windows BSOD on boot due to clear plastic tape on motherboard. Would boot and pass memtest86+ with no errors, but would consistently fail boot to Windows until tape removed from area opposite lower PCI slots. If I remember correctly, I could also successfully boot Linux while tape was present, but I may be mistaken as it's been a few years.

This issue was also present when booting a completely different hard drive with Windows 10, which usually would work fine on other systems.

Once tape was discovered and removed, normal boot was restored without incident.

BOFH's who want a good prank take note.