Some Possibilities:
Rogue (misbehaving) antivirus. IMHO always make it ASK to clean
Failing
internal Hard drive
Faulty (Mains) Power. A UPS is advised
The USER
messing with names in the Library folder
External storage issues:
Removing the drive BEFORE the 'Safe' message
Failing External drive (flash drives have higher fail rates)
Poor USB cable/connectors,
Marginal (USB self) powered drive Models
USB Hub congestion.
Using A Networked Drive
Allowing a Cloud drive to Sync TO the Active Library . Always pause Sync