System Crash

• If the device or computer the card was in crashed while accessing information on the card, this can corrupt both the data that was being accessed and the sectors on the card where the data was being stored. Sometimes this means a loss of data, other times it may damage the entire card to the point of it being unusable.
  
  

Viruses and Antiviruses

• Emil Sidos of Concept Data says that viruses and malfunctioning antivirus software can both lead to files becoming corrupt on storage media. Some viruses are programmed to seek out and destroy data so it becomes corrupted. Antivirus software should stop this, but sometimes antivirus software will mistakenly delete or modify a file that is not a virus, which can cause corruption of that file and other files that access it.
  
  

Physical Corruption

• A memory card that has been poorly handled can also sometimes become damaged to the point where corruption becomes a problem. If the card is cracked or scratched, this could lead to corruption or loss of data. Also, if the connectors it uses to transfer data to and from other devices become damaged, they could begin to transmit data incorrectly, causing files to become corrupt.