Filesharing over a network

Hey all, i have a server (windows server 2003) on the domain that is pretty much full of data for users to access and upload their files to. Recently we have noticed that everytime they open and save(close or w/e) few other files are created. a tmp file, few files with no extensions which have the same size as the original document. This is a pain and never seen it before. Anyone got an idea?