I suspect this may be caused by database corruption (FileVista.vdb4 file) and may not be related to uploaded files at all. Please try disabling logging for Upload event and if this fixes the issue, this proves the error happens when logging to the database. If this is the case, please send your database file to the support email and we will repair it.
Also let me know your FileVista version (you can check it from bin\GleamTech.FileVista.dll).