If you're writing an application that deals with files in file system on Windows, be sure that sooner or later you run into problems with antivirus software.

Our latest program that handles a lot of huge files and works as a Windows service, it reports time to time about some strange errors. These errors look like the file system disappeared on the fly, or, files were stolen by somebody else (after they have been opened in exclusive mode by our application).

We spent about two weeks in order to diagnose the cause of such behaviour, and then came to conclusion that is a secret work of our antivirus. All such errors disappeared as fog when the antivirus was configurated to skip folders with our files.

Thus, keep in mind our experience and don't allow an ativirus to became an evil.