No one can help you without knowing which file is being affected.
Four things come to mind if this keeps happening to you:
- When you have a fresh copy of EQ, take a copy of the file that gets affected and save it in a different folder, Backup if you will.
- Have you installed the updates to EQ, and if you have did you do it correctly? If this happens every time you update your files this may be a sign that you did not install the updates right.
- How are you updating your EQ files? Are you using the custom launcher or are you manually installing the files?
- What Anti-Virus program are you running and is it possible that it is deleting or changing the file because it thinks it is infected?
As I said before, cannot help you if we do not know which file is "corrupted".