My tf2 keeps on losing its files.

[Superbro11]

everytime when i play tf2, sometimes it crashes. then i verify the files. suddenly 1 or 2 files are gone or aka (failed to vaildate)
why?

[Ad Bot]

[Fab]

corrupted files, probably

[Afraidanna]

did you try reinstalling it

[Stick Man]

If you have Avast, it might be deleting important files because it thinks they are viruses.