Techniques are provided for desktop streaming over wide area networks. In one embodiment, a computing device comprises logic that is configured to intercept file open requests for files stored in a file system, where at least some of the files in the file system may have not yet been fully downloaded. In response to a request to open a file, the logic is configured to modify a first sharing mode specified therein and to open the file in a read-write sharing mode that allows other processes to open the file. While one or more blocks of the file are being downloaded or written into the file, the logic is configured to check whether a second sharing mode received in a subsequent request to open the file is compatible with the first sharing mode. If the second sharing mode is not compatible with the first sharing mode, the logic is configured to deny the subsequent request even though in the file system the file is opened in the read-write sharing mode.