Most players encounter this through Steam. Occasionally, during an update or initial download, a packet is dropped or a file is incorrectly hashed. Even a single bit of difference can cause the game's engine to reject the file as "corrupt." RAM and Overclocking Instability:
If verification fails, manually deleting the problematic file can force a clean download. bigfile000tiger tomb raider error
Sometimes Windows itself blocks the file. Most players encounter this through Steam