Some random questions:
1. Can you get me one of the corrupted proxies?
2. Are the proxies “read-only”? I.e. no-one modifies them when they are on the server.
3. Have you tried enabling read-only access to the server files?
4. What is the date of last modification for the corrupted files? Is it still the original creation date or newer?
Best regards,
Vlado