Windows Defender (or third-party AV) may lock .tiger files during scan. Add the entire game folder to exclusions: Settings → Privacy & Security → Virus & threat protection → Manage settings → Exclusions → Add exclusion (Folder) .

Whether you are launching the game for the first time or encountered this during a high-octane set piece, here is how to resolve the issue and get back to Siberia. Verify Game File Integrity