I have a document library where users upload zip files. The problem just started a few days ago.
Problem: When attempting to open the attached zip file, the following error message is recieved: "Cannot open file: it does not appear to be a valid archive. If you downloaded this file, try downloading the file again." It does not occur for every item, but random ones. Odd thing is, if I check out the file, check it back in, I will then be able to open the zip attachment. Another thing I noticed, and I'm not sure if this might be the cause of the error, but there is one specific user on my team who does NOT every get this error. He also, has some spreadsheet on his desktop that runs some macros which dowloads items from this library.