I would think that you could just try to open the file for exclusive read access - that should throw an exception. As for the ultimate, you would have to use interop and Win32 functions to delve into the finer details. The OpenFile() Win32 function might do a better job than .Net for what you want. This site really helps with the interop stuff.... http://pinvoke.net Jon Humphreys ActivePlanet Software Bangkok, Thailand