 <p>Well, for starters, you should not be writing anything to a folder in the Program Files directory. This is bad and will fail on Vista, Windows 7, or Windows Server 2008 and above.</p> <p>Secondly, your code isn't actually specifying what you think it is. The service's "current directory" is not it's program files directory. It's probably something like the users home directory that it runs under, or Windows\system32. Again, the app shouldn't have write persmissions there either. Instead, you should be loggint to somewhere like the Program Data subdirectires.</p>