As of yesterday, we cannot open any Office documents from the file server. If they try to open an Access database they get the error, "Unrecognized database format". If they try to open a Word document they get, "The file <filename> .docx cannot be opened because there are problems with the contents". In the details of the error it says, "The file is corrupt and cannot be opened".
We can open Office files that are saved on another server.
The other thing we have noticed is if we pull one of the files off the server onto a thumb drive, it still cannot be opened.