WotLK Has anyone noticed texture error crashes no matter the texture pack used?

[dantheman2016]

I have noticed that sporadically I am faced with a UI error "crash" associated with (random) textures "not found". I can paste a backup copy of the data folder from my original download. (my backup copy of files from warmane download that I suggest everyone do) This ALWAYS fixes the error present (no matter what texture it says is missing). My question is why does said file / files become corrupt / missing and what can I do to correct this?

[dantheman2016]

by the way this has happened when using warlords or wrath textures.....